System and method for UE context and PDU session context management

ABSTRACT

There is provided systems and methods for the grouping of UEs, such that UEs can share a UE group context or share a PDU session context or both. In this manner, network resource usage, with respect to UE context and PDU session context management, can be mitigated.

FIELD OF THE INVENTION

The present invention generally pertains to the field of communicationnetworks, and particular embodiments or aspects relate to management ofUE contexts and PDU session contexts.

BACKGROUND

Based on LTE network architecture, when a user equipment (UE) is turnedon and attaches to the network, the mobility management entity (MME)creates a UE context. The MME assigns a unique short temporaryidentifier termed the SAE temporary mobile subscriber identity (S-TMSI)to the UE that identifies the UE context in the MME. This UE contextholds user subscription information downloaded from the home subscribeserver (HSS). The local storage of subscription data in the MME allowsfaster execution of procedures such as bearer establishment since itremoves the need to consult the HSS every time. In addition, the UEcontext also holds dynamic information such as the list of bearers thatare established and the terminal capabilities. As would be readilyunderstood, this UE context information is also used by a base station,for example an evolved NodeB (eNB) associated or connected with the UE,for example eNB UE context which is a block of information in an eNBassociated to one active UE.

In addition, a UE receives services through a protocol data unit (PDU)session, which is a logical connection between the UE and the datanetwork. The UE requests the establishment of the PDU session and assuch, in the present context, the UE has an associated UE context and aPDU session context, which has to be stored and managed by thecommunication network in order to provide the UE with the desiredfunctionality.

The 3^(rd) Generation Partnership Project (3GPP) technical reportnumbered TR 23.799 and entitled “Study on Architecture for NextGeneration System,” version 14.0.0, December 2016 (hereinafter referredto as TR 23.799), represents one approach to the design of a systemarchitecture for next generation mobile networks, also referred to as5^(th) generation (5G) networks. In proposed “next generation” (NG)networks, such as 5G wireless communication networks, additionalflexibility and functionality is available to the network. Furthermore,it is proposed to have many more connections to the network as theInternet of Things (IoT) brings connectivity to a new range of devices.Moreover, in NG networks, it is supported that a UE can establishmultiple PDU sessions to the same data network. As such, there is a needto manage network resource usage, for example storage, computing andsignalling.

Accordingly, there may be a need for a system and method for themanagement of UE contexts or PDU session contexts or both, that is notsubject to one or more limitations of the prior art.

This background information is intended to provide information that maybe of possible relevance to the present invention. No admission isnecessarily intended, nor should be construed, that any of the precedinginformation constitutes prior art against the present invention.

SUMMARY

It is an object of the present invention to obviate or mitigate at leastone disadvantage of the prior art.

In accordance with an aspect of the present invention there is provideda method for selecting a network exposure function (NEF) in acommunication network. The method includes obtaining, by an applicationfunction (AF), information on a UE and information on a set of NEFs, theset of NEFs including one or more NEFs, selecting, by the AF, a NEFbased on the obtained information and enforcing, by the AF, the selectedNEF to serve the UE.

In accordance with an aspect of the present invention there is provideda network function including a network interface for receiving data fromand transmitting data to network functions connected to a network and aprocessor. The network function further including a non-transient memoryfor storing instructions that when executed by the processor cause thenetwork function to be configured to obtain information on a UE andinformation on a set of NEFs, the set of NEFs including one or moreNEFs, select a NEF based on the obtained information and enforce theselected NEF to serve the UE.

In some embodiments, the selected NEF is different from the source NEFserving the UE before the selection of the selected NEF. However, itwill be readily understood that the selected NEF may in fact be the sameNEF as the source NEF in instances where an improved choice for NEF doesnot exist. According to embodiments, the application function (AF)provides information to a common API framework (CAPIF) core function,wherein this information can be used for NEF selection. In someembodiments, the CAPIF core function may provide a list of suitable NEFsfrom which the AF can select the NEF. It is readily understood that oneor more of the above can be included in an embodiment.

In some embodiments, the obtaining information comprises receiving, bythe AF, a UE context of the UE. In some embodiments the information onthe NEF comprises one or more of following: PLMN ID, DNN, DNAI(s);application ID(s), AF-Service-Identifier; S-NSSAI, NSI-ID, UE groupID(s) including internal group ID, external group ID, IMSI group ID, UEID(s), AF ID, AF IP address, AF FQDN, UPF IP address, FQDN), AMF ID, AMFIP address, AMF FQDN, SMF ID, SMF IP address and SMF FQDN. In someembodiments, enforcing the NEF includes subscribing, by the AF, to eventexposure services of the selected NEF and sending, by the AF, aninfluence traffic routing request to the selected NEF. In someembodiments, before the selection the method includes subscribing, bythe AF, to event exposure services of the source NEF and sending, by theAF, an influence traffic routing request to the source NEF. In someembodiments, after the selection, the method includes unsubscribing, bythe AF, to event exposure services of the source NEF and canceling, bythe AF, the influence traffic routing request with the source NEF. Itwill be understood that the appropriate network function can beconfigured to perform the above noted further method steps. It isreadily understood that one or more of the above can be included in anembodiment.

In accordance with an aspect of the present invention there is provideda method for selecting a network exposure function (NEF) in acommunication network. The method includes selecting a NEF to serve a UEupon receiving a trigger, the trigger resulting from one or more of UEmobility, load balancing, relocation of a NEF, denial of service attack,a reselection request and enforcing a transmission of a UE context ofthe UE to the selected NEF.

In accordance with an aspect of the present invention there is provideda network function including a network interface for receiving data fromand transmitting data to network functions connected to a network and aprocessor. The network function further including a non-transient memoryfor storing instructions that when executed by the processor cause thenetwork function to be configured to select a NEF to serve a UE uponreceiving a trigger, the trigger resulting from one or more of UEmobility, load balancing, relocation of a NEF, denial of service attack,a reselection request and enforce a transmission of a UE context of theUE to the selected NEF.

According to some embodiments, the selection is performed by a sessionmanagement function (SMF). According to some embodiments thetransmission is between the selected NEF and a source NEF serving the UEbefore the selection. It is readily understood that one or more of theabove can be included in an embodiment.

According to some embodiments, the selection is performed by a commonAPI framework (CAPIF) core function. According to some embodiments, thetransmission is between the selected NEF and a UDR. It is readilyunderstood that one or more of the above can be included in anembodiment.

In accordance with an aspect of the present invention there is provideda method for network exposure function (NEF) relocation in acommunication network. The method includes receiving, by a NEF, a UEcontext of a UE and subscribing, by the NEF, to a service of a controlplane network function based on the received UE context of the UE.

In accordance with an aspect of the present invention there is provideda network function including a network interface for receiving data fromand transmitting data to network functions connected to a network and aprocessor. The network function further including a non-transient memoryfor storing instructions that when executed by the processor cause thenetwork function to be configured to receive a UE context of a UE andsubscribe to a service of a control plane network function based on thereceived UE context of the UE.

In some embodiments, the service of the control plane network functionsincludes one or more of subscribing, by the NEF, to event exposureservices of a session management function (SMF), subscribing, by theNEF, to event exposure services of an access management function (AMF),subscribing, by the NEF, to event exposure services of an unified datamanagement (UDM) function and subscribing, by the NEF, to event exposureservices of an policy control function (PCF). According to someembodiments, the UE context of the UE is received from a source NEFserving the UE or a unified data repository (UDR). In some embodiments,the NEF is selected by an application function (AF), or a sessionmanagement function (SMF), or a common API framework (CAPIF) corefunction to serve the UE as a source NEF after the selection. It will beunderstood that the appropriate network function can be configured toperform the above noted further method steps. It is readily understoodthat one or more of the above can be included in an embodiment.

In accordance with an aspect of the present invention there is provideda method for managing user equipment (UE) in a communication network.The method includes receiving, by a network function, a request from aUE, said UE belonging to a UE group and generating, by the networkfunction, a UE group context.

In accordance with an aspect of the present invention there is provideda network function including a network interface for receiving data fromand transmitting data to network functions connected to a network and aprocessor. The network function further including a non-transient memoryfor storing instructions that when executed by the processor cause thenetwork function to be configured to receive a request from a UE, saidUE belonging to a UE group and generate a UE group context.

According to some embodiments, the UE group context includes a UE groupidentifier. According to embodiments, the UE group context includes oneor more protocol data unit (PDU) session contexts, and their PDU sessionidentifiers. According to embodiments, the UE group context includes oneor more shared protocol data unit (PDU) session context and theiridentifiers. According to embodiments, the UE group context includes alist of UE IDs which are members of the UE group. It is readilyunderstood that one or more of the above can be included in anembodiment.

In accordance with an aspect of the present invention there is provideda method for managing user equipment (UE) in a communication network.The method includes receiving, by a network function, a requestincluding data indicative of a UE group and transmitting, by the networkfunction, a notification, the notification based upon the request andthe data.

In accordance with an aspect of the present invention there is provideda network function including a network interface for receiving data fromand transmitting data to network functions connected to a network and aprocessor. The network function further including a non-transient memoryfor storing instructions that when executed by the processor cause thenetwork function to be configured to receive a request including dataindicative of a UE group and transmit a notification, the notificationbased upon the request and the data.

According to some embodiments, the data includes a protocol data unit(PDU) session identifier. According to some embodiments, the dataincludes a shared protocol data unit (PDU) session identifier. Accordingto some embodiments, the request includes a request for modification ofa shared PDU session and wherein the notification includes a rejection.According to some embodiments, the request includes a network exposurefunction (NEF) relocation request and wherein the notification includesdata indicative of a UE group context and wherein the UE group contextincludes one or more of a UE group identifier, protocol data unit (PDU)session identifier and a shared PDU session identifier. It is readilyunderstood that one or more of the above can be included in anembodiment.

In accordance with an aspect of the present invention, there is provideda method for selecting or reselecting a network exposure function (NEF)in a communication network. The method includes receiving, by a targetapplication function (T-AF), a UE context, subscribing, by the T-AF, toevent exposure services of a source NEF and sending, by the T-AF, aninfluence traffic routing request to the source NEF. The method furtherincludes, upon determining a target NEF, subscribing, by the T-AF, toevent exposure services of the target NEF and sending, by the T-AF, aninfluence traffic routing request to the target NEF.

In accordance with an aspect of the present invention, there is provideda network function including a network interface for receiving data fromand transmitting data to network functions connected to a network, aprocessor and a non-transient memory for storing instructions. Theinstructions, when executed by the processor cause the network functionto be configured to receive a UE context, subscribe to event exposureservices of a source NEF and send an influence traffic routing requestto the source NEF. The instructions, when executed by the processorcause the network function to be configured to upon determination of atarget NEF, subscribe to event exposure services of the target NEF andsend an influence traffic routing request to the target NEF.

According to some embodiments, the method further includesunsubscribing, by the T-AF, to event exposure services of the source NEFand canceling, by the T-AF, the influence traffic routing request withthe source NEF. It will be understood that the appropriate networkfunction can be configured to perform the above noted further methodsteps. It is readily understood that one or more of the above can beincluded in an embodiment.

In accordance with an aspect of the present invention, there is provideda method for selecting or reselecting a network exposure function (NEF)in a communication network. The method includes receiving, by a targetNEF, a UE context transfer request, subscribing, by the target NEF, toservices of control plane network functions and sending, by the targetNEF, a UE context transfer response.

In accordance with an aspect of the present invention, there is provideda network function including a network interface for receiving data fromand transmitting data to network functions connected to a network, aprocessor and a non-transient memory for storing instructions. Theinstructions, when executed by the processor cause the network functionto be configured to receive a UE context transfer request, subscribe toservices of control plane network functions and send a UE contexttransfer response.

According to some embodiments, subscribing to services of control planenetwork functions includes one or more of subscribing, by the targetNEF, to event exposure services of a session management function (SMF),subscribing, by the target NEF, to event exposure services of an accessmanagement function (AMF), subscribing, by the target NEF, to eventexposure services of an unified data management (UDM) function andsubscribing, by the target NEF, to event exposure services of an policycontrol function (PCF). It will be understood that the appropriatenetwork function can be configured to perform the above noted furthermethod steps. It is readily understood that one or more of the above canbe included in an embodiment.

Embodiments have been described above in conjunctions with aspects ofthe present invention upon which they can be implemented. Those skilledin the art will appreciate that embodiments may be implemented inconjunction with the aspect with which they are described, but may alsobe implemented with other embodiments of that aspect. When embodimentsare mutually exclusive, or are otherwise incompatible with each other,it will be apparent to those skilled in the art. Some embodiments may bedescribed in relation to one aspect, but may also be applicable to otheraspects, as will be apparent to those of skill in the art.

Some aspects and embodiments of the present invention may provide areduction in network resource usage, with respect to UE context and PDUsession context management.

BRIEF DESCRIPTION OF THE FIGURES

Further features and advantages of the present invention will becomeapparent from the following detailed description, taken in combinationwith the appended drawings, in which:

FIG. 1 illustrates a method for UE context and PDU session contextmanagement, in accordance with embodiments of the present invention.

FIG. 2 is a method for UE context and PDU session context management, inaccordance with embodiments of the present invention.

FIG. 3 is a diagram illustrating an embodiment of interactions betweenthe Management Plane, Control Plane and User Plane of a network.

FIG. 4 illustrates a method for setup of UE group context in accordancewith embodiments of the present invention.

FIG. 5 illustrates a method of UE group context creation triggered by anetwork management function in accordance with embodiments of thepresent invention.

FIG. 6 illustrates a registration procedure of a UE with a (R)AN inaccordance with embodiments of the present invention.

FIG. 7 illustrates a UE-requested PDU session establishment fornon-roaming and roaming with local breakout in accordance withembodiments of the present invention.

FIG. 8 illustrates UE or network requested PDU session modification fornon-roaming and roaming with local breakout in accordance withembodiments of the present invention.

FIG. 9 illustrates a PDU session tunnel model according to the priorart.

FIG. 10 illustrates a shared tunnel for a hop on concept according toembodiments of the present invention.

FIG. 11 illustrates a hybrid PDU session tunnel according to embodimentsof the present invention.

FIG. 12. illustrates a method of NEF reselection in accordance withembodiments of the present invention.

FIG. 13 illustrates a model for selection or reselection of anapplication function (AF) and NEF, according to embodiments of thepresent invention.

FIG. 14. illustrates a method of NEF selection or reselection by an AFin accordance with embodiments of the present invention.

FIG. 15. illustrates a method of NEF selection or reselection by a CP inaccordance with embodiments of the present invention.

FIG. 16. illustrates a method of NEF relocation in accordance withembodiments of the present invention.

FIG. 17 is a block diagram of an electronic device within a computingand communications environment that may be used for implementing devicesand methods in accordance with representative embodiments of the presentinvention.

FIG. 18 illustrates a method of NEF selection or reselection inaccordance with embodiments of the present invention.

DETAILED DESCRIPTION

The present disclosure is directed to systems and methods for UE contextand PDU session management. It has been observed that with the increasein applications including IoT devices, there will be a large demand oncommunication network resources in order to provide a desired level ofservice for this increase in demand, for example the storage andsignalling of required by the network in order to manage UE context andPDU session context data for these UEs or electronic devices.Furthermore, it has been observed that particular groups of UEs orelectronic devices can have the same capabilities and subscribedservices. Thus there is provided systems and methods for the grouping ofUEs, such that UEs can share a UE group context or share a PDU sessioncontext or both. In this manner, network resource usage, with respect toUE context and PDU session context management, can be mitigated. It willbe readily understood that while it is envisioned that the term groupcan be used to define a plurality of UEs that share the same context,other terms may at least equally be used for example, collection of UEsor set of UEs.

According to embodiments, a UE requests that a new PDU session beestablished. A control plane (CP) function, for example a sessionmanagement function (SMF) can evaluate the request and determine if therequested new PDU session is to be a mapped to a new PDU session or toan existing shared PDU session. This mapping can be performed whereinthe SMF can map the PDU session ID, which is generated by the UE uponrequesting the PDU session, to the new PDU session or to an existing PDUsession that is to be shared amongst several UEs.

According to embodiments, by sharing PDU sessions for a group of UEs, ifa control plane (CP) network function (NF) needs to send one or morecontrol messages or modifications to a plurality of PDU sessions whichhappen to be all mapped to the shared PDU session, only a single controlmessage would have to be sent to modify the shared PDU session, insteadof control messages to each of the PDU sessions associated with theshared PDU session, or PDU sessions associated with UEs of a UE group.For example, the control plane function, for example a policy controlfunction (PCF), session management function (SMF), access managementfunction (AMF) or a network exposure function (NEF), would only have tosend one control message to modify the shared PDU session contextinstead of multiple control messages, each control message is to modifya PDU session context of an individual UE context. As such, according toembodiments, there can be a reduction in network resource usage formanagement of the UEs and PDU sessions, for example a reduction inrequired storage, computing and signalling. This reduction in networkusage can also be considered to be a reduction in internal operation ofUP and CP functions when modifying parameters of a large number of UEsand PDU sessions.

According to embodiments, there is provided a method for UE context andPDU session context management. With reference to FIG. 1, upon receiving101 a request from a UE which is a member of a UE group by a networkfunction, the network function proceeds to generate 102 a UE groupcontext which is indicative of the UE group. For example, the UE contextcan include data indicative of a UE group identifier (ID), one or morePDU session identifiers, which may include PDU session identifiers andshared PDU session identifiers, and a list of UE IDs which are membersof the UE group. In some embodiments, the UE group context can includedata indicative of quality of service (QoS) or charging policies or bothto be applied for PDU sessions or shared PDU sessions of UEs in the UEgroups. According to embodiments, the network function can be an accessmanagement function (AMF), session management function (SMF), networkexposure function (NEF), policy and control function (PCF), user planefunction (UPF), (Radio) Access Network ((R)AN) node, Unified DataRepository (UDR), Unified Data Management (UDM), Network Slice SelectionFunction (NSSF), NF repository function (NRF), or other networkfunctions.

According to embodiments, there is provided a method for UE context andPDU session context management. With reference to FIG. 2, upon receiving201 a request which includes data indicative of a UE group by a networkfunction (NF), the network function proceeds to transmit 202 anotification wherein this notification is based upon the request and thedata. For example, the data can include information indicative of a UEgroup, and the request is indicative of a modification of the servicefor the UEs which are included within the UE group. The informationindicative of the UE group can be considered as part of the UE groupcontext and the UE group context can include data indicative of one ormore of UE group identifier (ID), one or more of PDU session identifier,one or more of shared PDU session identifier and a list of UE IDs whichare members of the UE group. In some embodiments, the UE group contextcan include data indicative of quality of service (QoS) or chargingpolicies or both to be applied to a PDU session or shared PDU session ofthe member UEs of the UE group. According to embodiments, the networkfunction can be an AMF, SMF, NEF, PCF, UPF, (R)AN, UDR, UDM, NSSF, NRF,or other network functions.

In order to provide context to the instant application, which isdirected towards interactions between a UE and a communication network,FIG. 3 is provided to illustrate a network architecture 300 in which theresources of the operator network 302 are divided into a set of logicalplanes, a user plane (UP) 304, a control plane (CP) 306 and a managementplane (MP) 308. The UP 304 is typically focussed on packet transport,but certain functions including packet filtering and traffic shaping canbe performed in the UP 304, although this is typically performed basedon instructions from a network function in the CP 306. Functions in theMP 308 receive input from network functions within the customer domain310 about the policies that should be enforced by the network controlfunctions in the control plane 306. If Operator Network 302 supportsnetwork slicing, functions within MP 308 may be responsible for slicedesign and creation. It should be understood that a single MP 308 may beused to provide management functionality for a plurality of networkslices that each have different control and user planes. Functionswithin the MP 308 can communicate with each other to ensure that thediffering policies for a possible plurality of customers are fittedtogether in a suitable set of instructions.

UP 304 may also be referred to as a data plane. It carries the trafficbetween an ED 399 and either external data networks (not shown) orfunctions within the operator network. UP 302 is typically composed ofuser plane functions (UPFs) 314. As would be readily understood in someinstances, an ED can be a user equipment (UE). In some instances, a UPF314 may be specific to a particular UE, it may be specific to aparticular service (in some embodiments, it may be both user and servicespecific), and in other instances it may be a generic function serving aplurality of users and services. UPFs 314 are connected to each other toallow for data plane traffic to be transmitted. As would be readilyunderstood, there are one or more (R)AN nodes that are positionedbetween the UE and the UPF, which can at least in part provideinterconnectivity therebetween.

The control plane 306 may be composed of control plane functions (CPF)316. In a 3GPP compliant network, some control plane functions 316A havefunctions defined by standards, while other control plane functions 316Bmay be outside the specification of the relevant standards. This mayeffectively result in the control plane 306 being divided into astandards compliant control plane segment 306A and a non-standardscompliant control plane segment 306B. In a 3GPP compliant control planesegment 306A, network functions 316A such as an AMF, SMF, NEF,authorization and security function (AUSF), etc. may be present, and insome embodiments more than one instance of any or all of the functionsmay be present. In a non-standards compliant control plane segment 306B,a network function 316B such as a function to perform software-definednetwork (SDN) Controller, or other such controllers including aservice-oriented virtual network auto-creation operation (SONAC-Ops)controller, may be instantiated. Control plane functions 316, may beconnected to other CPFs, as shown by functions 316A, but this is notnecessarily required as may be seen by CPF 316B. ED 399 may alsocommunicate with CPFs.

The management plane 308 can be divided between a standards compliantsection 308A and a non-standards compliant section 308B, much as CP 306is divided. Within MP 308, network functions and nodes 318 cancommunicate with each other, and with a network function or node 312within the customer domain 310. Management plane entities 318A (withinthe standardized section 308A) and 318B (within the non-standardscompliant section 308B) can be used to establish policy, and themechanisms by which policy is to be enforced, based on the resourcesavailable and requirements received from the customer 312 (and possiblya plurality of different customers). Network management functions (NMF)318 may be responsible for accounting and billing functions, for elementmanagement, they may provide the services required for an operationsupport system (OSS) and a business support subsystem (BSS). Outside thestandardized functions, non-standardized network functions 318B mayinclude a network function virtualization management and orchestration(NFV-MANO) system and a service-oriented virtual network auto-creationcomposition (SONAC-Com) controller.

NMFs 318 can receive external input from a customer node 312, and cancommunicate with each other. NMFs 318 can also communicate, over any ofthe MP-CP connections 320, with CPFs 316 to provide instructions aboutthe policies to be enforced by CPFs 316. Changes in the resourcesunderlying the network 302 are also communicated by a NMF 318 to CPFs316. In CP 306, CPFs communicate with each other, and with ED 399. CPF316 are also in communication with UPFs 314 and with one or more (R)ANnodes, and through this communication they can receive information suchas traffic loads on links and processing loads at network functions. Inconjunctions with policy information received from NMFs 318, a CPF 316can transmit instructions to the UPFs 314, over the CP-UP (also referredto as UP-CP) connections 322, to govern the behavior of the UPFs 314. AUPF 314 receives configuration information from a CPF 318, and handlesUP traffic in accordance with the received configuration information.Loading information (which may include both processing and networkconnection (or link) loading) may be gathered by a UPF 314 and providedto a CPF 316.

In some embodiments, the customer network function 312 may have aconnection to a CFP 316. This CPF, with which customer network function312 communicates, may be either a 3GPP compliant CPF 316A or a non-3GPPcompliant CPF 316B. In alternate embodiments, the customer networkfunction 312 may make use of a function within management plane 308 torelay messages to functions in control plane 306. Within the customerdomain 310, there may be an optional control plane 324, with customercontrol plane functions 326 and 328. When such a customer control plane324 is present, function 326 and 328 may have logical communicationslinks with either or both of ED 399 and the customer network function312. Customer control plane functions 326 and 328 may have connectionsto functions within control plane 306 (either 3GPP compliant functions316A or non-3GPP compliant functions 316B).

According to embodiments, the UE group context is created in controlplane functions which can include the AMF, SMF, PCF, UDM, UDR, NEF,NSSF, NRF, and the application function (AF). The UE group context isalso created in user plane functions which can include the (radio)access network ((R)AN) node, access node (AN) and UPF. It will bereadily understood that while the term UE group context is used todefine a plurality of UEs that share the same context, other terms mayat least equally be used to defined the same feature, for example, UEshared context, UE collection context, UE set context or the like.

According to embodiments, the UE group context can be created inadvance, for example by preconfiguration of the UDM or UDR or by anetwork management function (NMF) with the required information relatingto the UE group context. For example, the UE group context can includeinformation relating to one or more of: UE group identifier (ID), listof member UE IDs, PDU session group IDs, quality of service (QoS),charging policies or other features of the UE group context which isassociated with each of the member UEs. According to embodiments, the UEgroup context can be created by the control plane functions and the userplane functions upon receipt of a request, such as request from the AF,or the UE, or the NMF.

According to embodiments, a number of different UEs are defined as beingmembers of a particular UE group, and this UE group can have anassociated UE group ID. According to embodiments, a UE group context canbe created by the AMF. In this instance, when a first UE of a particularUE group registers with the communication network the AMF can create theUE group context in the AMF. According to some embodiments, when a firstUE of a particular UE group requests a PDU session, there is anassociated PDU session context. In instances where this PDU sessioncontext can be shared, for example as a shared PDU session context, theSMF creates a UE group context in the SMF. The SMF further requests the(R)AN, and UPF to establish a UE group context and/or shared PDU sessioncontext. According to some embodiments, when the AF sends the firstrequest to the NEF for a UE group, the UE group context is created inthe NEF. In some embodiments, when a first control plane function, forexample the AMF, SMF or PCF, subscribes to the NEF for the notificationservice for relevant events or actions in relation to a particular UEgroup, the UE group context is created in the NEF. As the UE groupcontext is created and stored in the NEF this can provide for areduction in required signalling.

According to some embodiments, the NEF is preconfigured to serve aparticular UE group and the AF can send a request to the NEF in order toinitiate the NEF transmitting a request to set up a UE group context.For example, with reference to FIG. 4, the AF 425 sends 401 an AFrequest, wherein this request carries information of member UEs of aparticular UE group. The request may include a transaction ID torepresent this request, and information including one or more of: anexternal group identifier to identify the UE group, a list of externalUE IDs or GPSI (Generic Public Subscription Identifier), a packet filterset or Packet Flow description (PFD) to identify downlink trafficintended to one or some or all UEs of UE group (e.g. application serverIP address(es) or IP prefixes), port numbers, QoS information (e.g.maximum bit rate for each UE, maximum aggregated bit rate of all UEs,packet delay budget, packet error rate), DNAI (data network accessidentifier).

The NEF 424 subsequently sets up a UE group context for that particularUE group. An authentication and authorization procedure 402 is initiatedbetween the AF 425, NEF 424, AUSF 423 and UDM 422 or UDR or both. Duringprocedure 402, either the UDM or UDR may assign an internal group ID,which is mapped to the external group ID. The UDM or UDR informs the NEF424 the internal group ID. Upon completion of the authentication andauthorization procedure 402, the NEF 424 transmits 403 an AF requestresponse which may indicate that the control plane is setting up the UEgroup context.

The NEF 424 subsequently selects 404 the UDM/UDR 422 for the setting upof the UE group context. The NEF 424 sends 405 an application dataupdate request indicative of the UE group context to the UDM/UDR 422.The NEF 424 may provide some or all information received from the AF425, such as the packet filter set or PFD, and QoS requirementsinformation to the UDR.

The UDM and/or UDR may send a response message 406 to the NEF. Theresponse message may include the Internal group ID if this parameter wasnot sent in procedure 402.

The UDM/UDR 422 transmits 407 an application data change notificationwhich is indicative of the UE group context to the PCF 421. The message407 may include the internal group ID, application ID, PFD or packetfilter sets for both uplink (UL) and downlink (DL) directions,authorized QoS parameters for the member UEs (such as maximum bit rate(MBR), maximum flow bit rate (MFBR), guaranteed flow bit rate (GFBR),session-aggregated maximum bit rate (session-aggregated maximum bit rate(AMBR)), packet delay budget (PDB)), and for the UE group (e.g. UEgroup-AMBR), charging policy (e.g. UE group-based charging in which thecharging is applied to all UEs in the UE group as a whole, not forindividual UEs).

If the message 407 carry data change notification and the Internal groupID only, the PCF 421 may send a request to the UDM and/or UDR to providethe data of Internal group ID. The PCF 421 may generate in step 408 newUE related policy and UE group related policies by using the informationprovided by the UDM/UDR 422. The PCF 421 subsequently transits 409 apolicy update notification to the SMF 420, which currently serve UEs ofUE group, wherein the policy update notification is indicative of the UEgroup context. The PCF 421 may also send other messages (not shown inFIG. 4) to other network entities such as the AMF (that currently serveUEs of UE group) to update access and mobility policies, to the UE forUE route selection policy (URSP). The CP functions may create UE groupcontext after receiving UE group information from the PCF. The PCF 421may also send notification message to NSSF, which include Internal groupID and member UEs of internal group. When an CP function is selectedlater, the NSSF may use the UE group information to make sure that thesame SMF or AMF is used to serve all the UEs of UE group that arecurrently associated to the (R)AN nodes that are in the same servicearea of the AMF or in the same service area of the SMF.

According to some embodiments, the messages exchanged among NFs in FIG.4 and other figures as present in the instant application, can bealternatively implemented by using existing or new service-basedinterface services of NFs.

FIG. 5 illustrates a method of UE group context creation triggered by anetwork management function in accordance with embodiments of thepresent invention. The network management function (NMF) 508 sends 511to the UDM (or UDR) 506 a message as an Internal UE groupcreation/modification/deletion request. The message may include the listof UE IDs (e.g. permanent equipment identifier (PEI), subscriberpermanent identifier (SUPI), IMSI, GPSI), or the network sliceinformation (e.g. S-NSSAI, NSSAI), device owner identifier, applicationidentifier, and other information to filter the UEs. The message mayinclude default CP network functions to serve the UE group. The UDM (orUDR) 506 confirms the reception of the message by sending a response 512to the NMF 508. The UDM (or UDR) 506 creates 513 an UE group context inUDM (or in UDR) 506, represented by a unique UE group ID (such asinternal group ID). The UE group context may be stored in either theUDM, or UDR, or both the UDM and UDR. The UE context may include the UEIDs of UEs in the group, and other related information from the servicesubscription information. The UDM (or UDR) 506 sends 514 to the PCF 504a message as a UE group policy creation/modification/deletion request.The message may include UE group ID, UE IDs of UE group, servicesubscription information. The PCF 504 creates a UE group context. The UEgroup context may include UE group ID, UE IDs, and UE group policiessuch as QoS policy, charging policy, network slice selection policy, UEtraffic routing policy (such as UE route selection policy (URSP)). ThePCF 504 sends 515 to UDM 506 a message as a UE group policycreation/modification/deletion request to confirm the reception ofmessage. The UDM 506 may request 516 other CP functions tocreate/modify/delete UE group context.

Optionally, in some embodiments, for UE group context creation, the UDM506 may use the network function information provided by the NMF 508 toidentify the CPF 502. Alternatively, the UDM may discover the CPfunction by getting information from network repository function (NRF).If the UE group context has been created in CPF 502, the CPF mayregister themselves to the UDM. The UDM can provide UE group updates tothe CPF 502 by modify/delete messages.

According to embodiments, once the CPFs are selected to serve a specificUE group, the UDM may inform the NRF which CP functions are selected toserve the UE group. The message from the UDM to the NRF may include theUE group ID, application ID, and UE IDs. The information on the UE groupand UE IDs, application ID and other information available in the NRF(such as network slice information) can be used for CP NF selection,such as AMF, SMF and PCF, so that the same set of CP NFs may be selectedto serve all UEs of a UE group in some geographic area, or in the sameregistration area managed by a specific AMF. In some embodiments, the UEgroup information (e.g. including UE group ID, UE IDs of UE group,application ID) may be preconfigured by the NMF 508 in the NRF.

With further reference to FIG. 5, the CPF 502 sends 517 to the UDM 506 amessage as a UE group creation/modification/deletion response for themessage received. The CPF 502 may send 518 to the PCF 504 a message as aUE group policy creation/modification/deletion request. According toembodiments, for new a UE group, the CPF requests the PCF to send UEgroup policies. The policies may include policies that apply to all theUEs of the UE group, and/or policies that apply to individual UEs. TheCPF also register itself with the PCF in order to get policy updates.According to embodiments, for an existing UE group, if the PCF does notsend policy updates to CPF, the CPF may request the PCF to send updatedpolicies. According to embodiments, if the UE group is deleted, the CPFcan request the PCFs to remove their subscription from policy updateservices of the PCF. The PCF 504 sends 519 to CPF 502 a message as a UEgroup policy creation/modification/deletion request to acknowledge thereception of message.

According to some embodiments, the UE group context includes informationindicative of the UE group ID, a list of UE IDs of each UE that is amember of the UE group and a list of PDU session group IDs. In thisembodiment, a UE can have a particular PDU session ID associatedtherewith, wherein this PDU session ID is mapped to a PDU session groupID. The PDU session group ID identifies a PDU session that is sharedbetween several UEs that are assigned to the UE group ID. As all UEswithin the group do not necessarily share the same PDU session having aparticular PDU session group ID, there can be plural PDU session groupIDs associated with a particular UE group context. According toembodiments, the PDU session context, which can be associated with aparticular UE, can include information indicative PDU sessioninformation and a mapping between the PDU session ID with the associatedUE group ID and PDU session group ID.

According to some embodiments, the UE group context includes informationindicative of a list of UE IDs of each UE that is a member of the UEgroup, UE group related information which can include one or more ofQuality of Service, charging policies and other US group relatedinformation. The UE group context can further includes informationindicative of the shared PDU session context which can be identified bythe shared PDU session ID that is generated by the SMF. In theseembodiments, each UE has a UE context with includes a PDU sessioncontext and a shared PDU session context. In addition, the shared PDUsession context includes a mapping of the PDU session ID generated bythe UE with the UE group ID and the shared PDU session ID. According tothese embodiments, the configuration of a UE group context and sharedPDU session context can be applied to UEs, for example smart phones orother wireless devices, that have enhanced mobile broadband (eMBB)applications and massive IoT (MIoT) applications. In some instancesthese applications may occur at the same time.

According to some embodiments, the UE group context includes informationthat is indicative of the individual UE contexts of the UEs that havebeen assigned to the UE group, UE group related information which caninclude one or more of Quality of Service, charging policies and otherUS group related information. The UE group context can further includeinformation indicative of the shared PDU session context which can beidentified by the shared PDU session ID that is generated by the SMF.According to these embodiments, the configuration of a UE group contextcan be applied to UEs which relate to one or more applications, such asmassive IoT (MIoT) applications.

According to embodiments, The UE context may include PDU sessionpointers pointing to memories of non-shared PDU sessions and shared PDUsessions. The PDU session pointers of multiple UE contexts can point tothe same memory of shared PDU sessions. The (R)AN, UPF, AMF, SMF andother functions have a mapping of UE-generated PDU session ID andSMF-generated PDU session ID. The (R)AN, UPF, AMF and other functionsmay use the SMF address (such as IP address or FQDN) and shared PDUsession ID to locate the data of shared PDU session. The SMF uses theshared PDU session ID to locate the context data of shared PDU sessions.

According to embodiments, one or more of the following parameters may bestored in the PDU session context of UE context at the SMF, AMF, UPF and(R)AN. The type of PDU session can be stored in the PDU session context,for example a non-shared PDU session or a shared PDU session. The PDUsession ID may also be present in the PDU session context, for examplefor a non-shared PDU session, the PDU session ID can be UE-generated.For a shared PDU session, the PDU session ID can be UE-generated and SMFgenerated. The PDU session pointer may be stored in the PDU sessioncontext. For a non-shared PDU session, the PDU session pointer may pointto a separate memory of PDU data structure. For a shared PDU session,the PDU session pointer may point to a common memory of PDU datastructure. For example, the UE group ID and shared PDU session ID canuniquely identify the mapping between UE-generated session ID andSMF-generated shared PDU session ID. An example of a pointer can be aUE-generated PDU Session ID mapped to <UE Group ID, SMF-generated PDUSession ID>. The type of UP connection may be stored in the PDU sessioncontext, wherein the UP connection can be shared or non-shared.According to some embodiments, the PDU session context can includeadditional information elements, such as SMF ID (or SMF address) or AMFID (or AMF address), depending on the network functions.

In additional to the individual UE context, the AMF, SMF, (R)AN, and UPFand other network functions may have a UE group context. The UE groupcontext can include information elements that includes one or more of UEgroup ID, UE members, shared PDU session ID, serving SMF ID (oraddress), serving AMF ID (or address), S-NSSAI and the type of UPconnection. The UE group ID can be unique in a PLMN, or unique within anetwork slice. The UE members can be list of UE IDs of the UE group. Theshared PDU session ID can be the ID generated by the serving SMF and itcan be unique within one UE group. The serving SMF can have a SMF ID (oraddress) and the serving AMF can have an AMF ID (or address). TheS-NSSAI can represent network slice information and the UP connectiontype can be shared or non-shared.

According to embodiments, in the (R)AN, UPF, AMF, SMF and other networkfunctions, a UE information may be stored in a separate UE context or ina UE group context or in a separate UE context and a UE group context.If the UE has a non-shared PDU session, the UE information may be storedin a separate UE context. If the UE belongs to a UE group, the UEinformation may be stored in a UE group context. The UE group contextmay include individual UE context profiles of all UEs in this group.Alternatively, the UE context profile may have pointers pointing to theUE group context profile.

According to some embodiments, when all UEs of a UE group have onlyshared PDU sessions, it is more efficient to have a single UE groupcontext in UP and CP functions. The UE group context contains allindividual UE information. When the 5G CP or UP functions want to makechanges to all the UEs of the UE group, the UE group ID may be used tosend messages to all the UE in the UE group. The UE group contextincludes the UE context of all of the member UEs. The UE group contextcan include a UE group ID which can be unique within one PLMN, or uniquewithin a network slice instance; UE members, which can be a list ofmember UE IDs; UE context of each UE member which can include a securitycontext, except for a shared PDU session context; shared PDU sessioncontexts which can define the PDU sessions that are shared among UEs ofthe UE group; and policies applied to shared PDU sessions for examplepolicies for individual UEs and for UE groups.

According to embodiments, when a control plane function or a user planefunction are to transmit a message or signal for a UE group, the messageor signal can include information that is indicative of the UE group IDand the shared PDU session ID. In this manner by sending a singlemessage, the operation of plural UEs and their associated PDU sessionscan be modified, thereby reducing the signalling that is required tomake these changes to network operation.

However, in some embodiments, if a particular UE requests a modificationto a PDU session associated therewith, and this PDU session is a sharedPDU session, namely multiple UEs are using the same PDU session, thecontrol network may reject this requested modification. For example, ifa UE requests changes to certain control parameters of the PDU session,for example allocation and retention priority (ARP), maximum bit ratepacket delay or other control parameters that can result in changes tothe PDU session that would affect other UEs, the control network willreject the requested modification.

According to embodiments, the shared PDU session ID is generated by acontrol plane function, for example the SMF, which can be associatedwith a plurality of specific PDU sessions being used by multiple UEs andthere is no change with respect to the UE. For example, a UE can requestthe establishment of a new PDU session which has a UE generated PDUsession ID. The control plane function, for example the SM, canassociate or map this UE generated PDU session ID with a SMF generatedPDU session ID, for example a shared PDU session ID. It is understoodthat the shared PDU session ID can be unique within the particular SMF,unique within a plurality of SMFs associated with the communicationnetwork, or unique within a network slice instance, or unique withrespect to PLMN network. Furthermore, it will be understood that whilethese embodiments have been discussed with respect to the SMF, the SMFmay be replaced by another control plane function, for example the AMF,PCF, UDM, NEF or the like.

FIG. 6 illustrates a registration procedure of a UE with a (R)AN inaccordance with embodiments of the present invention. According toembodiments, the procedure illustrated in FIG. 6 provides a method tocreate UE group context in the AMF when the first UE of a UE groupregisters to the CN. When the UE performs initial attachment, the UE maysend device class to the (R)AN and the (R)AN can inform the AMF about UEdevice class. It is understood that device class may also be referred toas UE device class. The UDM provides UE group ID and UE IDs members. ThePCF provides UE group policies. The AMF may request the (R)AN to createUE group context, which store the access and mobility policies of the UEgroup.

With reference to FIG. 6 the method includes the UE sending 621 amessage in as a registration request to the (R)AN 604. The message caninclude (AN parameters, RM-NAS registration request (registration type,SUPI or 5G-GUTI, security parameters, NSSAI, UE 5GCN capability, PDUsession status, PDU session(s) to be re-activated, UE device class,follow on request, and MICO mode preference)). In the case of 5G-RAN,the AN parameters can include e.g. SUPI or the 5G-GUTI, the selectednetwork and NSSAI, UE device class. In case of NG-RAN, the AN parameterscan also include establishment cause. The establishment cause providesthe reason for requesting the establishment of an RRC connection. Theregistration type indicates if the UE wants to perform an “initialregistration” (i.e. the UE is in RM-DEREGISTERED state), a “mobilityregistration update” (i.e. the UE is in registered state and initiates aregistration procedure due to mobility) or a “periodic registrationupdate” (i.e. the UE is in registered state and initiates a registrationprocedure due to the periodic update timer expiry). The UE can performan initial registration (i.e., the UE is in RM-DEREGISTERED state) to aPLMN for which the UE does not already have a 5G-GUTI, the UE shallinclude its SUPI in the registration attempt. In other cases, the5G-GUTI is included which indicates the last serving AMF. If the UE isalready registered via a non-3GPP access in a PLMN different from thenew PLMN (i.e. not the registered PLMN or an equivalent PLMN of theregistered PLMN) of the 3GPP access, the UE may not provide over the3GPP access the 5G-GUTI allocated by the AMF during the registrationprocedure over the non-3GPP access. Also, if the UE is alreadyregistered via a 3GPP access in a PLMN (i.e. the registered PLMN),different from the new PLMN (i.e. not the registered PLMN or anequivalent PLMN of the registered PLMN) of the non-3GPP access, the UEwill not provide over the non-3GPP access the 5G-GUTI allocated by theAMF during the registration procedure over the 3GPP access. The securityparameters are used for authentication and integrity protection. NSSAIindicates the network slice selection assistance information. The PDUsession status indicates the previously established PDU sessions in theUE. The PDU session(s) to be re-activated is included to indicate thePDU session(s) that the UE intends to activate. The follow on request isincluded when the UE has pending uplink signalling and the UE doesn'tinclude PDU session(s) to be re-activated. The UE device class can beoptional and it indicates the UE capabilities to assist (R)AN to selecta pre-configured AMF. The UE device class is also to assist so that theAMF to select a pre-configured SMF function or NSSF function.

If a SUPI is included or the 5G-GUTI does not indicate a valid AMF the(R)AN, based on (R)AT and NSSAI and/or UE device class, if available,selects an AMF 622. The process by which the (R)AN selects an AMF canproceed as is known. If the (R)AN cannot select an appropriate AMF, itforwards the registration request to an AMF which has been configured,in (R)AN, to perform AMF selection. In some embodiments, the NMF maypreconfigure the UE group information in the (R)AN 604 with thefollowing information: UE group ID, UE IDs of UE group, network sliceinformation (e.g. S-NSSAI) and a default or pre-configured AMF that isdedicated to serve the UE group. If the (R)AN 604 receives theinformation from the UE in message 621 that matches the UE groupinformation, the (R)AN 604 can select the pre-configured AMF to servethe UE 602.

The (R)AN 604 sends 623 a message as a registration request to the newAMF 606. The message can include (N2 parameters, RM-NAS registrationrequest (registration type, subscriber permanent identifier or 5G-GUTI,security parameters, NSSAI and MICO mode preference, UE device class)).When 5G-RAN is used, the N2 parameters include the location information,cell identity and the RAT type related to the cell in which the UE iscamping. When NG-RAN is used, the N2 parameters also include theestablishment cause. The message in 623 may include UE group information(such as UE group ID). If the registration type indicated by the UE isperiodic registration update, then steps 624 to 637, referred to below,may be omitted.

In some embodiments, the new AMF 606 sends 624 a message as a UE contexttransfer request to the old AMF 608. The message can be aNamf_Communication_UE_Context_Transfer (complete registration request).If the UE's 5G-GUTI was included in the registration request and theserving AMF has changed since last registration, the new AMF may invokethe Namf_Communication_UEContextTransfer service operation on the oldAMF including the complete registration request IE, which may beintegrity protected, to request the UE's SUPI and MM Context. The oldAMF uses the integrity protected complete registration request IE toverify if the context transfer service operation invocation correspondsto the UE requested. The old AMF also transfers the event subscriptionsinformation by each consumer NF, for the UE, to the new AMF.Subsequently, the old AMF 608 sends 625 a UE context transfer responsewhich can be a response to Namf_Communication_UEContextTransfer whichcan include (SUPI, MM Context, SMF information). The old AMF can respondto the new AMF for the Namf_Communication_UEContextTransfer invocationby including the UE's SUPI and MM context. If the old AMF holdsinformation about active PDU sessions, the old AMF includes SMFinformation including SMF identities and PDU session identities. If theold AMF holds information about active N2AP UE-TNLA bindings to N3IWF,the old AMF includes information about the N2AP UE-TNLA bindings.

In some embodiments, the new AMF 606 sends 626 an identity request tothe UE 602. If the SUPI is not provided by the UE nor retrieved from theold AMF the identity request procedure is initiated by AMF sending anidentity request message to the UE. The UE 602 may send 627 an identityresponse to the new AMF wherein the identity response can include theSUPI. In some embodiments, the AMF 606 may decide to invoke an AUSF 628,wherein the AMF, based on SUPI, can select an AUSF as is known. The AUSFmay initiate authentication 629 of the UE. If network slicing is used,the AMF can decide if the registration request needs to be rerouted. TheAMF can also initiate NAS security functions.

In some embodiments, new AMF 606 sends 630 a message to the old AMF 608wherein the message is a Namf_Communication_RegistrationCompleteNotify () If the AMF has changed the new AMF notifies the old AMF that theregistration of the UE in the new AMF is completed by invoking theNamf_Communication_RegistrationCompleteNotify service operation. If theauthentication/security procedure fails, then the Registration shall berejected, and the new AMF invokes theNamf_Communication_RegistrationCompleteNotify service operation with areject indication reason code towards the old AMF. The old AMF continuesas if the UE context transfer service operation was never received. Insome embodiments, the new AMF 606 sends 631 an identity request to theUE 602. If the PEI was not provided by the UE nor retrieved from the oldAMF the identity request procedure is initiated by AMF sending anidentity request message to the UE to retrieve the PEI.

In some embodiments, the new AMF 606, based on the SUPI or UE deviceclass or both, selects 633 a UDM 616. If the AMF 606 knows that the UEbelongs to a UE group, the AMF 606 may select the same UDM 616 thatserves other UEs of the same UE group. If the AMF has changed since thelast registration, or if the UE provides a SUPI which doesn't refer to avalid context in the AMF, or if the UE registers to the same AMF it hasalready registered to a non-3GPP access (i.e. the UE is registered overa non-3GPP access and initiates this registration procedure to add a3GPP access), the new AMF 606 invokes 634 a theNudm_UEContextManagement_Registration service operation towards the UDM616. If there is no subscription context for the UE in the AMF, the“subscription data retrieval indication” is included. The new AMFprovides the access type it serves for the UE to the UDM and the accesstype is set to “3GPP access”. The UDM stores the associated access typetogether with the serving AMF. For the other UEs of the UE Group, theAMF does not need to obtain the UE Context information if there are nochanges to the UE group subscription. If “the subscription dataretrieval” indication was included in step 634 a, the UDM invokes 634 bthe Nudm_SubscriptionData_UpdateNotification service operation toprovide the subscription data from the UDM. The new AMF creates an MMcontext for the UE after getting the mobility related subscription datafrom the UDM. The subscription data may include UE device class and UEgroup information. The UE group information include UE group ID, UE IDsof the UE group (e.g. SUPI). The UE group ID indicates that the UEs ofthe same UE group ID have the same network control policies, such asaccess, mobility, QoS policies. If the UE group Context does not exist,the AMF creates the UE group context for the UE group. When the UDM 616stores the associated access type together with the serving AMF asindicated in step 634 a, it will cause the UDM to initiate 634 c aNudm_UEContextManagement_RemoveNotification to the old AMF 608corresponding to 3GPP access, if one exists. The old AMF removes the MMcontext of the UE. If the serving NF removal reason indicated by the UDMis “initial registration”, then the old AMF invokes theNamf_EventExposure_Notify service operation towards all the associatedSMFs of the UE to notify that the UE is de-registered from old AMF. TheSMF shall release the PDU session(s) on getting this notification.

In some embodiments, the new AMF 606, based on the SUPI, selects a PCFin 635. If the AMF 606 knows that the UE belongs to a UE group, the AMF606 may select the same PCF 610 that has been selected (orpre-configured) to serve the UEs of the UE group. The new AMF 606 sends636 a message to the PCF 610, wherein the message is aNpcf_PolicyControl_PolicyCreate (SUPI). If the AMF has not yet obtainedaccess and mobility policy for the UE or if the access and mobilitypolicy in the AMF are no longer valid, the AMF requests the PCF to applyoperator policies for the UE by creating a policy control session withthe PCF through the Npcf_PolicyControl_PolicyCreate service operation.In the roaming case, the interaction between H-PCF and V-PCF is requiredfor the provision of the access and mobility policy. The PCF sends aresponse to the new AMF wherein the response is aNpcf_PolicyControl_PolicyCreate (access and mobility policy data). ThePCF responds to the Npcf_PolicyControl_PolicyCreate service operationand provides the access and mobility policy data for the UE to the AMF.

In some embodiments, new AMF sends a message to the SMF wherein themessage is a Namf_EventExposure_Notify ( ) The AMF invokes theNamf_EventExposure_Notify in one or more of situations: 1) If the AMF ischanged, the new AMF notifies each SMF of the new AMF serving the UE byinforming the UE reachability status including the PDU session statusfrom the UE relevant for each SMF. In case the AMF has changed, it isassumed that the old AMF provides the available SMF information. Basedon the PDU session status provided by the new AMF checks the PDU sessionstatus and in the Namf_EventExposure_Notify service operation the SMFeither re-activates the PDU sessions by to complete the user plane(s)setup without sending MM NAS service accept from the AMF to (R)AN orreleases any network resources related to PDU sessions that the UEindicated as not established; and 2) If the UE was in MICO mode and theAMF had notified an SMF of the UE being unreachable and that the SMFdoes not need to send DL data notifications to the AMF, the AMF informsthe SMF that the UE is reachable; and 3) If the AMF had notified an SMFof the UE being reachable only for regulatory prioritized service andthe UE enters into allowed area, the AMF informs the SMF that the UE isreachable. According to embodiments, the AMF will also notify any otherNF that subscribed to UE reachability that the UE is reachable.According to embodiments, if an SMF has subscribed to UE location changenotification via Namf_EventExposure_Subscribe service operation and ifthe AMF detects that the UE has moved out the area of interestsubscribed by an SMF serving the UE, the AMF invokesNamf_EventExposure_Notify service operation to inform the SMF of the newlocation information of the UE. According to embodiments, the SMF maydecide to trigger, for example new intermediate UPF insertion or UPFrelocation. According to embodiments, if the registration type indicatedby the UE is periodic registration update, then steps 640 and 641 may beomitted.

According to embodiments, the new AMF sends 638 a N2 Request( ) to N3IWF618. The AMF may decide to modify the N2AP UE-TNLA-binding toward N3IWF.This is done in case AMF is changed and old AMF have existing N2APUE-TNLA-bindings toward a N3IWF for the UE. The N3IWF 618 can send 639 aN2 Response( ) to the new AMF 606.

In some embodiments, the old AMF 608 sends 640Npcf_PolicyControl_PolicyDelete ( ) to the PCF 610. If the old AMFpreviously requested UE context to be established in the PCF, the oldAMF terminates the UE context in the PCF by invoking theNpcf_PolicyControl_PolicyDelete service operation. The PCF 610 can senda Npcf_PolicyControl_PolicyDelete ( ) response to old AMF 608.

According to embodiments, the new AMF 606 sends 641 a registrationaccept message to the UE 602. The message can include (5G-GUTI,registration area. mobility restrictions, PDU session status, NSSAI,periodic registration update timer, LADN information and accepted MICOmode, UE group information (e.g. UE group ID, application ID)). The AMFsends a registration accept message to the UE indicating that theregistration has been accepted. 5G-GUTI is included if the AMF allocatesa new 5G-GUTI. Mobility restrictions included in case mobilityrestrictions applies for the UE. The AMF indicates the established PDUsessions to the UE in the PDU session status. The UE removes locally anyinternal resources related to PDU sessions that are not marked asestablished in the received PDU session status and for which the UE hasrequested PDU session establishment and not received SMF response. Ifthe PDU session status information was in the registration request, theAMF shall indicate the PDU session status to the UE. The NSSAI includesthe allowed S-NSSAIs. If the UE subscription data includes subscribedLADN identification information, the AMF can include in the registrationaccept message the LADN Information for LADNs that are available withinthe registration area determined by the AMF for the UE. If the UEincluded a MICO mode in the request, then AMF responds whether MICO modeshould be used. When the follow on request is included, the AMF can notrelease the signalling connection immediately after the completion ofthe registration procedure.

In some embodiments, the AMF 606 sends 642 to the (R)AN 604 a message toestablish UE context. The message includes UE device class, 5G GUTI,S-NSSAI, UE group context information (UE group ID, UE IDs of UE group,application ID, UE group access and mobility policies), securityinformation. If the UE group context has been created by shared PDUsession pre-configuration procedure, the (R)AN associates the UE withthe group UE context. The UE group context may contain a pre-configuredN3 shared tunnel. If the UE group context does not exist, the AMF maysend to the (R)AN UE group context information, including UE groupaccess and mobility policies. The AMF may include the list of UEs(including SUPI of UEs) of the same UE group ID. The AMF may alsoinclude security information to the (R)AN. The (R)AN 604 sends 643 aresponse message to the AMF 606. If the UE group context does not exist,the (R)AN may create DL TEID and send (R)AN tunnel information to theAMF.

In some embodiments, the UE 602 sends 644 a registration completemessage to the AMF 606. The UE sends a registration complete message tothe AMF to acknowledge if a new 5G-GUTI was assigned. When the “PDUsession(s) to be re-activated” are not included in the registrationrequest, the AMF releases the signalling connection with the UE. Whenthe follow on request is included in the registration request, the AMFcan not release the signalling connection immediately after thecompletion of the registration procedure.

FIG. 7 illustrates a UE-requested PDU session establishment fornon-roaming and roaming with local breakout in accordance withembodiments of the present invention. According to embodiments, there isprovided methods to create UE group context in SMF and UPF functions. Inthese embodiments, the shared PDU session is not pre-configured. The UEsends a request to the SMF to establish a PDU session after successfulregistration. The AMF and SMF create shared PDU session context whenreceiving the PDU session establishment request from the first UE of theUE group ID. FIG. 7 illustrates a method used to establish a new PDUsession as well as to hand over an existing PDU Session between 3GPPaccess and non-3GPP access. In case of roaming, the AMF determines if aPDU session is to be established in local breakout (LBO) or homerouting. In the case of LBO, the procedure is as in the case ofnon-roaming, however the SMF, UPF and PCF are located within the visitednetwork.

With further reference to FIG. 7, there is an assumption that the UE hasalready registered on the AMF thus the AMF has already retrieved theuser subscription data from the UDM. The UE 702 sends 721 a PDU sessionestablishment request to the AMF 706. The UE can send a NAS messagewhich includes (S-NSSAI, DNN, PDU session ID, request type, N1 SMinformation, UE device class, UE group information (UE group ID,application ID)). The UE group information (UE group ID, application ID)may be included if the UE knows its UE group ID and application ID. Inorder to establish a new PDU session, the UE generates a new PDU sessionID. The UE initiates the UE requested PDU session establishmentprocedure by the transmission of a NAS message containing a PDU sessionestablishment request within the N1 SM information. The PDU sessionestablishment request may include a PDU type, SSC mode, protocolconfiguration options. The request type indicates “initial request” ifthe PDU session establishment is a request to establish a new PDUsession and indicates “existing PDU session” if the request refers to anexisting PDU session between 3GPP access and non-3GPP access. Therequest type indicates “emergency request” if the PDU sessionestablishment is a request to establish a PDU session for emergencybearer services. The request type indicates “existing emergency PDUsession” if the request refers to an existing PDU session for emergencyservices between 3GPP access and non-3GPP access. The NAS message sentby the UE can be encapsulated by the AN in a N2 message towards the AMFthat should include user location information and access technology typeinformation. The N1 SM information may contain SM PDU DN requestcontainer containing information for the PDU session authorization bythe external DN. The AMF receives from the AN, the NAS SM message (builtin step 721) together with user location information (e.g. cell ID incase of the RAN). The UE shall not trigger a PDU session establishmentfor a PDU session corresponding to a LADN when the UE is outside thearea of availability of the LADN. The UE device class is optional. TheUE can provide UE device class, which may also be referred to as deviceclass, so that the AMF can select a SMF and suitable methods to assignIP address/IP prefix, policy, QoS, UP management procedures. If thedevice class is sent from the UE, for some device classes, one or moreof the following pieces of information may be omitted, DNN, S-NSSAI, PDUSession ID. If the AMF knows the device class, which has been providedby either the UE or the UDM, the device class may be omitted.

According to embodiments, the AMF 706 determines that the messagecorresponds to a request for a new PDU session based on that requesttype indicates “initial request” and that the PDU session ID that is notused for any existing PDU session(s) of the UE. If the NAS message doesnot contain an S-NSSAI, the AMF may determine a default S-NSSAI for therequested PDU session either according to the UE subscription, if itcontains only one default S-NSSAI, or based on the operator policy. TheAMF selects 722 a SMF. The AMF stores an association of the PDU sessionID and the SMF ID. The case where the request type indicates “existingPDU session”, and either the AMF does not recognize the PDU session IDor the subscription context from UDM does not contain an SMF IDcorresponding to the DNN constitutes an error case. If the request typeindicates “emergency request” or “existing emergency PDU session”, theAMF selects the SMF taking this type of request into account. Based onone or more of the S-NSSAI, device class and UE group ID, the AMFselects a SMF to serve the UE. The AMF 706 may select the same SMF thathas been pre-configured in the AMF or in the NRF, or has been selectedto serve other UEs of the UE group.

According to embodiments, the AMF 706 sends 723 aNsmf_PDUSession_CreateSMRequest which can include (SUPI, DNN, S-NSSAI,PDU session ID, AMF ID, request type, device class, UE group ID,existing shared PDU session IDs, N1 SM information (PDU sessionestablishment request), user location information, access technologytype, PEI, PCF ID, UE group information (e.g. UE) to the SMF 710. ThePCF ID is the ID of the PCF that has been selected by the AMF 706 toserve the UE or to serve all the UEs of UE group. The AMF ID uniquelyidentifies the AMF serving the UE. The AMF forwards the PDU session IDtogether with the N1 SM information containing the PDU sessionestablishment request received from the UE. The device class may beoptional. The SMF may obtain device class later when accessing UDM.Based on one or more of S-NSSAI, device class, and DNN, the AMF mayselect an UE group ID and include existing shared PDU session IDs ofthis UE group. The UE group ID(s) indicates that the UE belongs to a UEgroup. If the SMF already obtained UE subscription data, sessionmanagement, QoS, and charging policies for the UE group ID, the SMF maynot need to access the either the UDM or PCF to get the UE information.

In some embodiments, if the SMF has not yet registered and subscriptiondata is not available, then the SMF 710 registers 724 a-724 b with theUDM 714, retrieves subscription data and subscribes to be notified whensubscription data is modified. If the request type indicates “existingPDU session” the SMF determines that the request is due to handoverbetween 3GPP access and non-3GPP access. The SMF identifies the existingPDU session based on the PDU session ID. subscription data includes theauthorized PDU type(s), authorized SSC mode(s), default 5QI/ARP,subscribed session-AMBR, UE group ID, UE group AMBR. The SMF checkswhether the UE request is compliant with the user subscription and withlocal policies. If the DNN corresponds to an LADN, the SMF verifieswhether the UE is located within the LADN service area based on the UElocation reporting from the AMF. If that is not the case the SMF rejectsthe UE request via NAS SM signalling by responding to the AMF withNsmf_PDUSession_CreateSMResponse including a relevant SM rejectioncause. The SMF indicates to the AMF that the PDU session ID is to beconsidered as released, it deregisters from UDM and the rest of themethod is skipped. The UE group AMBR is the aggregated maximum bit rateof the UE group ID. The group AMBR is enforced by the (R)AN and UPF. Ifthe UE belongs to a UE group and the SMF already has subscription datafor the UE group ID, the SMF does not need to perform this registrationwith the UDM. If the UE is the first UE of a UE group, the SMF obtainsUE subscription data, UE group data from the UDM and stores thisinformation in the UE group shared session context. The SMF may create ashared PDU session ID as part of UE group shared PDU session context.The SMF stores the mapping between the shared PDU session ID andUE-generated PDU session IDs.

According to some embodiments, the UDM 714 may inform the SMF 710 aboutthe PCF 712, which has been selected by the AMF 706 to serve the UE.

According to embodiments, if the SMF needs to perform secondaryauthorization/authentication 725 during the establishment of the PDUsession by a DN-AAA server, the SMF selects an UPF and triggers the PDUsession establishment authentication/authorization. If the PDU sessionestablishment authentication/authorization fails, the SMF terminates thePDU session establishment procedure and indicates a rejection to the UE.The secondary authorization/authentication may be applied to individualUEs of the same UE group ID.

According to embodiments, if dynamic PCC is deployed, the SMF 710performs PCF selection 726 a. The SMF may select the same PCF that canbe defined either by the AMF 706 in message 723 or defined by the UDM714 in step 724. If dynamic PCC is not deployed, the SMF may apply localpolicy. The SMF may use one or both of UE group ID and device class toselect a PCF. The SMF 710 may invoke 726 b the Npcf_SMPolicyControl_Getoperation to establish a PDU-CAN session with the PCF 712 and get thedefault PCC rules for the PDU session. If the request type indicates“existing PDU session”, the SMF may notify an event previouslysubscribed by the PCF by invoking the Nsmf_EventExposure_Notifyoperation and the PCF may update policy information in the SMF byinvoking Npcf_SMPolicyControl_UpdateNotify operation. The PCF mayprovide authorized session-AMBR and the authorized 5QI/ARP to SMF. Ifthe UE belongs to a UE group and this UE is the first UE requesting PDUsession establishment, the SMF establishes a PDU-CAN shared session withthe PCF and gets the default PCC rules for the PDU shared session. ThePCC rules include the rules for individual UE and the rules for the UEgroup. The PCF 712 subscribes to the IP allocation/release event in theSMF 710 (and may subscribe other events) by invoking 726 c theNsmf_EventExposure_Subscribe operation. A purpose of steps 726 a-726 cis to receive PCC rules before selecting UPF. If PCC rules are notneeded as input for UPF selection, these steps can be skipped. Forunstructured PDU session, the PCF may subscribe to the IPallocation/release event of N6 UPD/IP interface.

According to embodiments, if the request type indicates “initialrequest”, the SMF selects an SSC mode for the PDU session. If step 725is not performed, the SMF 710 also selects 727 an UPF. In case of PDUtype IPv4 or IPv6, the SMF allocates an IP address/prefix for the PDUsession. For unstructured PDU type the SMF may allocate an IPv6 prefixfor the PDU session and N6 point-to-point tunnelling (based onUDP/IPv6). If the request type indicates “emergency request” or“existing emergency PDU session”, the SMF selects the UPF in accordancewith the request type. For the first UE of a UE group ID requesting PDUsession establishment, the SMF may allocate an IP address or IP prefixfor the PDU session and N6 IP/UDP point-to-point tunnel. The SMF mayalso assign a flow label of N6 IP/UDP tunnel. For other UEs of the sameUE group ID requesting PDU, the SMF may allocate a new IP address or IPprefix for the PDU session and N6 IP/UDP point-to-point tunnel.Alternatively, the SMF may use the same IP address/IP prefix for N6IP/UDP tunnel, but assign another flow label for the N6 IP/UDP tunnelfor the PDU session for each UE. The SMF may select whether a shared ULand DL UP connections based on UE mobility information received fromAMF, QoS and charging policies, and legal interception requirements. Thefollowing combinations of N3 and N9, and N6 tunnels are possible, butnot limited to: 1) UL and DL N3 and N9 tunnels are shared; 2) UL N3 andN9 tunnels are shared and the DL N3 and N9 tunnels are not shared; 3) N6tunnel is shared or not shared.

According to some embodiments, the SMF 710 may select the same UPF 708to serve the UEs of the UE group. If an intermediate UPF (I-UPF) (notshown in FIG. 7) is required to provide connection between the (R)AN 704and the PDU session anchor (PSA) UPF, the SMF 710 may select the sameI-UPF to serve the UEs that are in the service area of the I-UPF or inthe service area of the PSA UPF 708.

According to embodiments, the SMF 710 may invoke 728 a theNsmf_EventExposure_Notify service operation to report some event to thePCF that has previously subscribed. If request type is “initial request”and dynamic PCC is deployed and PDU type is IPv4 or IPv6, SMF notifiesthe PCF (that has previously subscribed) with the allocated UE IPaddress/prefix. The PCF may provide authorized session-AMBR and theauthorized 5QI/ARP to SMF. For the UE group, the SMF may notify the PCFthe IP address or IP prefix of the UE and/or IP address/IP prefix of theN6 IP/UDP tunnel. The PCF has a mapping of IP address of IP prefix ofUEs of the same UE group. The PCF 712 may provide updated policies tothe SMF by invoking 728 b the Npcf_SMPolicyControl_UpdateNotify serviceoperation. For the UE group, if the PCF has already provided SMF withPCC rules for individual UEs and UE group, this step may be skipped. ThePCF may use the UE group ID to send one message to the SMF to modify PCCrules for all UEs of the same UE group.

According to embodiments, if request type indicates “initial request”and step 725 was not performed, the SMF initiates an N4 sessionestablishment procedure with the selected UPF, otherwise it initiates anN4 session modification procedure with the selected UPF. The SMF 710sends 729 a a N4 session establishment/modification request to the UPFand provides packet detection, enforcement and reporting rules to beinstalled on the UPF 708 for this PDU session. If CN tunnel informationis allocated by the SMF, the CN tunnel information is provided to UPF inthis step. If UE belongs to a UE group, the CN tunnel information may bealready established for the UE group ID. The SMF sends and N4 sessionmodification request to the UPF. The message includes the UE group ID,shared PDU session ID, UL TEID, DL TEID. If the UE belongs to a UE groupand the CN tunnel is not established, the SMF sends an N4 Sessionestablishment to the SMF. The message includes UE group ID, list of UE(indicated by e.g. SUPI) in the UE group, and PCC rules for individualUE and UE group. The SMF may include the DL TEID if the SMF knows theexisting shared DL N3 tunnel. Otherwise, the (R)AN may generate a new DLTEID at a later point. The SMF may include a UL TEID. The UL TEID maybelong to an existing shared N3 tunnel or a new non-shared N3 tunnel.The UPF 708 acknowledges by sending 729 b an N4 sessionestablishment/modification response. If CN tunnel information isallocated by the UPF, the CN tunnel information is provided to SMF inthis step.

According to some embodiments, the SMF 710 may assign the same tunnelendpoint ID (TEID) for the shared N3 and N9 tunnels in the UL. If the(R)AN assigns the DL N3 TEID, the SMF may assign the same TEID for DL N9TEID as DL N3 TEID. The (R)AN 704 and UPF 708 may perform packetaggregation to send aggregated PDUs in the UL and DL N3 and N9 sharedtunnels.

According to some embodiments, if the PDU session of the UE hasnon-shared N3 and N9 tunnels, the SMF 710 may assign the same TEID forthe non-shared UL N3 and UL N9 tunnels. The (R)AN 704 may assign theTEID for the DL N3 tunnel, the SMF may use the same DL N3 TEID for theDL N9 TEID.

According to embodiments, the SMF 710 sends 731 aNsmf_PDUSession_CreateSM response which can include (cause, N2 SMinformation (PDU session ID, QoS profile(s), CN tunnel information,S-NSSAI, session-AMBR, UE group ID, group-QoS profile(s), PDU sharedsession ID, DL TEID), N1 SM information (PDU session establishmentaccept (authorized QoS rule, SSC mode, S-NSSAI, allocated IPv4 address,session-AMBR))) to the AMF 706. The N2 SM information carriesinformation that the AMF shall forward to the (R)AN can include one ormore of the CN tunnel information corresponds to the core networkaddress of the N3 tunnel corresponding to the PDU session, the QoSprofile provides the (R)AN with the mapping between QoS parameters andQoS flow identifiers. multiple QoS profiles can be provided to the(R)AN, the PDU session ID may be used by AN signalling with the UE toindicate to the UE the association between AN resources and a PDUsession for the UE, the S-NSSAI is corresponding to the PDU session, theN1 SM information contains the PDU session establishment accept that theAMF shall provide to the UE, and the multiple authorized QoS rules maybe included in the PDU session establishment accept within the N1 SMinformation and in the N2 SM information, the SM response furthercontains PDU session ID and information allowing the AMF to know whichthe target UE as well to determine which access towards the UE to use.It is understood that the access information is to deal with the casewhere a UE is simultaneously connected over 3GPP and non 3GPP access.The SMF shall subscribe to the UE location reporting in case ofsuccessful PDU session establishment providing reporting criteria (e.g.UE location with respect to the area of LADN availability for a LADN).If the UE PDU session belongs to a PDU shared session, the SMF includesUE group ID and/or PDU shared session ID. If the UE is the first UE of aUE group requesting PDU session establishment, the SMF also includesgroup QoS profile(s). For other UEs of the same UE group ID and PDUshared session ID, the group QoS profile(s) may be also include the DLTEID is included if the N3 tunnel is shared. The DL TEID is the TEID ofthe existing shared N3 tunnel. In addition, for some device classes, theSMF may not send one or more of the following to the UE in the NASmessage: authorized QoS rule, SSC mode, S-NSSAI, allocated IPv4 address,session-AMBR.

According to embodiments, the AMF 706 sends 731 a N2 PDU session requestwhich can include (N2 SM information, NAS message (PDU session ID, PDUsession establishment accept)), to the (R)AN 704. The AMF sends the NASmessage containing PDU session ID and PDU session establishment accepttargeted to the UE and the N2 SM information received from the SMFwithin the N2 PDU session request to the (R)AN. The (R)AN 704 may issue732 an AN specific signalling exchange with the UE 702 that is relatedwith the information received from SMF. For example, in case of a 3GPPRAN, an RRC connection reconfiguration may take place with the UEestablishing the necessary RAN resources related to the authorized QoSrules for the PDU session request received in step 730. (R)AN alsoallocates (R)AN N3 tunnel information for the PDU session. In case ofdual connectivity, the master RAN node may assign some (zero or more)QFIs to be setup to a master RAN node and others to secondary RAN node.The RAN tunnel information includes a tunnel endpoint for each involvedRAN node, and the QFIs assigned to each tunnel endpoint. A QFI can beassigned to either the master RAN node or the secondary RAN node and notto both. (R)AN forwards the NAS message (PDU session ID, N1 SMinformation (PDU session establishment accept)) provided in step 730 tothe UE. (R)AN can provide the NAS message to the UE if the necessary RANresources are established and the allocation of (R)AN tunnel informationare successful.

According to embodiments, the (R)AN 704 sends 733 a N2 PDU sessionresponse which can include (PDU session ID, cause, N2 SM information(PDU session ID, (R)AN tunnel information, list of accepted/rejected QoSprofile(s))) to the AMF 706. The (R)AN tunnel information corresponds tothe access network address of the N3 tunnel corresponding to the PDUsession. The UE may be assigned a separate N3 tunnel or a shared N3tunnel. If the SMF has not indicated shared DL TEID in step 730, the(R)AN may include a DL TEID in the (R)AN tunnel information. If UEbelongs to a UE group ID and the (R)AN shared N3 tunnel for this UEgroup has been established, the N2 SM information may be omitted.

According to embodiments, the AMF 706 sends 734 aNsmf_PDUSession_UpdateSMContext request (N2 SM information) to the SMF710. The AMF forwards the N2 SM information received from (R)AN to theSMF. If the UE PDU session belongs to a PDU shared session ID and theSMF already has the (R)AN N3 shared tunnel information, this step may beskipped. If the N4 session for this PDU session was not establishedalready, the SMF initiates an N4 session establishment procedure withthe UPF. Otherwise, the SMF initiates an N4 session modificationprocedure with the UPF. The SMF provides AN tunnel information and CNtunnel information. The CN tunnel information only needs to be providedif the SMF selected CN tunnel information. If the PDU sessionestablishment request was due to mobility between 3GPP and non-3GPPaccess, the downlink data path is switched towards the target access inthis step. If the UE PDU session belongs to a PDU shared session and theSMF already notified UPF about (R)AN N3 shared tunnel information, thisstep and step 735 b may be skipped. The UPF 708 provides 735 b a N4session establishment/modification response to the SMF.

According to some embodiments, the SMF 710 may assign the same tunnelendpoint ID (TEID) for the shared N3 and N9 tunnels in the UL. If the(R)AN assigns the DL N3 TEID, the SMF may assign the same TEID for DL N9TEID as DL N3 TEID. The (R)AN 704 and UPF 708 may perform packetaggregation to send aggregated PDUs in the UL and DL N3 and N9 sharedtunnels.

According to some embodiments, if the PDU session of the UE hasnon-shared N3 and N9 tunnels, the SMF 710 may assign the same TEID forthe non-shared UL N3 and UL N9 tunnels. The (R)AN 704 may assign theTEID for the DL N3 tunnel, the SMF may use the same DL N3 TEID for theDL N9 TEID.

According to embodiments, the SMF 710 sends 736 aNsmf_PDUSession_UpdateSMContext response (cause) to the AMF 706. Afterthis step, the AMF forwards relevant events to the SMF, e.g. at handoverwhere the (R)AN tunnel information changes or the AMF is relocated. Inaddition, if step 734 is skipped then step 736 is also skipped. In someembodiments, in the case of a PDU type IPv6, the SMF 710 generates anIPv6 router advertisement and sends it to the UE 702 via the UPF 708.

According to embodiments, if the PDU session establishment request isdue to a handover between 3GPP access and non-3GPP access, i.e. therequest type is set to “existing PDU session” the SMF 710 performs stepsin order to release 738 the user-plane over the source access (3GPP ornon-3GPP access). If the SMF identity is not included in the DNNsubscription context, either stored already in SMF if it was previouslyregistered or provided in steps 724 a-724 b by the UDM, the SMF 710invokes 739 the Nudm_UEContextManagement_Update service operationincluding the SMF address, the DNN and the PDU Session Id. The UDMstores the SMF identity, SMF address and the associated DNN and PDUSession Id.

According to embodiments, if during the procedure the PDU sessionestablishment is not successful, the SMF informs the AMF. Once the AMFassociates an SMF with a PDU session ID, the SMF is automaticallysubscribed to notifications of incoming N1 signalling associated withthis PDU session ID. These notifications automatically provide any userlocation information and Access Type that the AMF has received from the(R)AN in association with N1 signalling.

FIG. 8 illustrates UE or network requested PDU session modification fornon-roaming and roaming with local breakout in accordance withembodiments of the present invention. The UE 802 initiates the PDUsession modification procedure by the transmission 821 a of a PDUsession modification request as an NAS message which can include (N1 SMinformation (PDU session modification request), PDU session ID) messageto the AMF 806. Depending on the access type, if the UE was in CM-IDLEmode, this SM-NAS message is preceded by the service request procedure.The N1 message is forwarded by the (R)AN to the 5G core with anindication of user location information. The AMF 806 invokes 821 b aNsmf_PDUSession_UpdateSMContext (PDU session ID) which is transmitted tothe SMF 808. The PCF 812 invokes 821 c theNpcf_SMPolicyControl_UpdateNotify service operation to notify SMF 808for initiating the modification of policies procedure upon policydecision or upon AF requests and the modification requires signalling tothe UE and/or to the AN. It is noted that for a UE group, the PCF mayuse shared PDU session ID or UE group ID to modify PCC rules formultiple UEs and/or multiple PDU sessions. The UDM 812 updates 821 d thesubscription data of SMF 808 by Nudm_SubscriberData_UpdateNotification(SUPI, Subscription Data). The SMF updates the subscription data andacknowledges the UDM by returning an acknowledgement with output (SUPI).It is noted that for a UE group, the UDM may use UE group ID to updatesubscription data for multiple UEs. The SMF may use UE group ID whenacknowledging the request of UDM. The SMF 808 may decide to modify PDUsession. This procedure also may be triggered based on locallyconfigured policy. If the SMF receives a trigger 821 e in step 821 a to821 d, the SMF starts SMF requested PDU session modification. Ifnotification control is configured for a GBR flow, when the (R)ANdecides the QoS targets of the flow cannot be fulfilled. (R)AN 804 sends821 f the N2 message (PDU session ID, N2 SM information) to the AMF 806.The N2 SM information includes the QFI, user location information and anotification indicating that the QoS targets cannot be fulfilled. TheAMF 806 invokes 821 g Nsmf_PDUSession_UpdateSMContext (N2 SMinformation) which is transmitted to the SMF 808.

According to embodiments, the SMF 808 may need to report some subscribedevent to the PCF 814 by invoking 822 a Nsmf_EventExposure_Notify serviceoperation. The PCF may provide new policy information to the SMF byinvoking Npcf_SMPolicyControl_UpdateNotify service operation. This stepmay be skipped if PDU session modification procedure has been triggeredin a previous step. If dynamic PCC is not deployed, the SMF may applylocal policy to decide whether to change the QoS profile. For shared PDUsession, the SMF use UE group ID and/or shared PDU session ID to reportto PCF for subscribed events.

According to embodiments, steps 823 to 827 are not invoked when the PDUsession modification requires only action at an UPF, for example gating.

According to embodiments, for UE initiated modification, the SMF 808responds 823 a to the AMF 806 through Nsmf_PDUSession_UpdateSMContext(N2 SM information (PDU session ID, QoS profile, session-AMBR), N1 SMinformation (PDU session modification command (PDU session ID, QoS rule,session-AMBR))). The N2 SM information carries information that the AMFshall provide to the (R)AN. It includes the QoS profiles that wereadded, removed or modified. The N1 SM Container carries the PDU sessionmodification command that the AMF shall provide to the UE. For networkinitiated modification, the SMF 808 invokes 823 bNamf_Communication_N1N2MessageTransfer (N2 SM information (shared PDUsession ID, PDU session ID, QoS profile, session-AMBR, shared QoSprofile, shared session AMBR), N1 SM container (PDU session modificationcommand (PDU session ID, QoS rule, session-AMBR))) transmission to theAMF 806. If the UE is in CM-IDLE state and an ATC is activated, the AMFupdates and stores the UE context based on theNamf_Communication_N1N2MessageTransfer and steps 824, 825, 826 and 827can be skipped. When the UE is reachable e.g. when the UE entersCM-CONNECTED state, the AMF forwards the N1 message to synchronize theUE context with the UE. For shared PDU Session, the SMF may includeshared PDU session ID and shared QoS profile, shared session AMBR. ThePDU session ID may be omitted. For some device class, the N1 SMcontainer may be omitted.

According to embodiments, the AMF 806 may send 824 N2 PDU sessionrequest (N2 SM information received from SMF, NAS message (PDU sessionID, N1 SM information (PDU session modification command))) message tothe (R)AN 804. The (R)AN 804 may issue 825 AN specific signallingexchange with the UE 802 that is related with the information receivedfrom SMF. For example, in case of a 3GPP RAN, an RRC connectionreconfiguration may take place with the UE modifying the necessary RANresources related to the PDU session. The UE acknowledges the PDUsession modification command by sending a NAS message (PDU session ID,N1 SM information (PDU session modification command Ack)) message. Forshared PDU session, the (R)AN uses the shared PDU session ID to identifythe impacted UEs' PDU sessions and apply the changes to all UEs' PDUsessions.

According to embodiments, the (R)AN 804 may acknowledge N2 PDU sessionRequest by sending 826 a N2 PDU session Ack (QFI(s), RAN tunnelinformation, NAS message, user location Information) message to the AMF806. In case of dual connectivity, if one or more QFIs were added to thePDU session, the master RAN node may assign one of these QFIs to a RANnode which was not involved in the PDU session earlier, then the RANtunnel information includes a new N3 tunnel endpoint for QFIs assignedto the new RAN node. Correspondingly, if one or more QFIs were removedfrom the PDU session, a RAN node may not be involved in the PDU sessionanymore, and the corresponding tunnel endpoint is removed from the RANtunnel information. The AMF 806 forwards 827 the N2 SM information andthe N1 SM information (PDU session modification command Ack) receivedfrom the AN to the SMF 808 via Nsmf_PDUSession_UpdateSMContext serviceoperation. The SMF 808 may update N4 session of the UPF(s) that areinvolved by the PDU session modification by sending 828 a N4 sessionmodification request (N4 Session ID) message to the UPF 810. The UPF 810can subsequently send 828 b a N4 session modification response to theSMF 808. For shared PDU sessions, the SMF may use shared PDU session IDto update the shared PDU session context, which shall apply new PCCrules to multiple UEs' PDU sessions. The UPF that are impacted in thePDU session modification procedure depends on the modified QoSparameters and on the deployment. For example, in the case of thesession AMBR of a PDU session with an UL CL changes, only the UL CL isinvolved.

According to embodiments, if the SMF interacted with the PCF in step 821c or 822 a, the SMF 808 notifies 829 the PCF 814 whether the PCCdecision could be enforced or not by invoking Nsmf_EventExposure_Notifyservice operation. The SMF can notify entities that have subscribed touser location information related with PDU session change.

FIG. 9 illustrates a PDU session tunnel model according to the priorart. Current 3GPP systems, 3G/4G/5G, employ per PDU Session tunnelbetween a (R)AN 902 and a UP 904. Each PDU session has two dedicatedtunnels in the UL 910, 920 and DL 912, 922. The UL and DL tunnels arereassigned when the UE moves to a new (R)AN node.

FIG. 10 illustrates a shared tunnel for a hop on concept according toembodiments of the present invention. To avoid signaling overhead, thehop-on concept proposes that the UP tunnels can be preconfigured, forexample UL shared tunnel 1010 and DL shared tunnel 1020. When the UE isattached to the network, the UE can be associated with thepre-configured tunnels.

However, if the UPF needs the UE ID, represented by TEID for trafficrouting and charging. When a shared tunnel is used, the UE ID may becarried in the tunnel header. This may increase the tunnel overhead. Inaddition, the UPF may need to know the UE location to forward the DLpackets. In the hop-on concept, the (R)AN may send a message to the UPFin the UL tunnel to inform the UPF of the new UE location. However, in5G, the UE location update is performed in the CP. Thus, this mayrequire signaling from the (R)AN to the AMF, then AMF to SMF, then SMFto UPF for UE location update.

FIG. 11 illustrates a hybrid PDU session tunnel according to embodimentsof the present invention. According to embodiments, the UL and DL tunnelmodels can be different. For example, the UL tunnel can be shared tunnel1110, while the DL tunnel is per PDU session tunnel, for example DL PDUsession tunnel 1120 and DL PDU session tunnel 1122. This configurationcan be suitable for the scenario that all the UPFs do not require UE IDto forward UL packets to the application server. The DL tunnel is notshared so that the UE mobility can be easily handled by the existingsolutions already provided for in the 3GPP systems. According toembodiments, it is desired to support mobility UE and the hybrid PDUsession tunnel can provide for the UL traffic of many UEs to be sent tothe same application server using the pre-configured shared UPconnections and the DL UP connection can be dedicated to each UE tosupport mobility.

According to embodiments, the NEF can be pre-configured by the networkmanagement function to serve one or multiple groups of UE, one ormultiple network slice instances, one or multiple applications, one ormultiple local area data networks (LADN) and one or multiple datanetworks (DN). The NEF may register itself to the NF repository function(NRF). The NEF can be selected or reselected by CP network functions,such as AMF or SMF or UDM or PCF or the NEF itself. The selection orreselection of the NEF may be determined by the one or more of: DNN,LADN, network slice information (e.g. S-NSSAI), UE ID, UE location, UEgroup identifiers (e.g. internal group ID, external group ID), UE groupsubscription information, SMF service area, UPF service area, ASlocation (e.g. DNAI) and geographical zone identifiers, application ID.

In order to discover which AMF and SMF functions which serve specificUEs, the NEF may need to access the UDM or UDR. According toembodiments, the NEF can send a notification message received from an AFto the serving UDM, PCF, AMF or SMF for the UE group, rather thansending individual messages for each of the UEs. When the UE isregistered to the network, the AMF accesses UE subscription informationin the UDM and/or UDR and knows about UE Group ID and the pre-configuredNEF. If it is the first UE of the UE group, the AMF may subscribe toevent notification service of the NEF for specific events such asmobility information of the UE group. The AMF can register to the UDMthat this AMF serves the UE group. When the UE requests for PDU sessionestablishment, the AMF selects a SMF to serve the UE and/or the UE groupthat includes this UE. The SMF accesses the UDM to obtain UEsubscription information and also the information about UE group ID andthe NEF function that serves the UE or the UE group. The SMF maysubscribe to the event notification service of NEF for some events suchas AF requests for DNAI reselection. The SMF can register to the UDMthat this SMF servers the UE group.

According to embodiments, in some instances due to UE mobility, and/orapplication server mobility, or denial-of-service (DoS) attack, or loadbalancing, or NEF maintenance, and other reasons, a particular NEF maynot be an optimal NEF for servicing a particular UE or UE group of UEsand as such here can be a need for reselection of the NEF for the UEgroup. For example, in a vehicle to everything (V2X) situation, the UEor the whole UE group is indicative of the IoT devices associated with aparticular vehicle and this vehicle is travelling. In this situation theNEF can be used to send control or data messages from the AF orapplication server (AS) of V2X application to the specific UEs or allthe UEs of UE group of IoT devices. As this vehicle is travelling, theNEF may need to be reselected in order that the NEF is positioned at amore suitable location along the mobility path of the vehicle. In thisexample, a control plane function, for example the SMF can determinethat NEF reselection is required and proceed with the reselection of amore suitable NEF. As another example, a need for reselection of the NEFservicing a UE group can be a result of load balancing. Other instanceswhere NEF reselection may be required would be readily understood by aworker skilled in the art.

FIG. 12 illustrates an example of a process of selection or reselectionof the NEF servicing a group of UEs. In this example, the SMF 1223determines 1201 that NEF reselection is required and further selects atarget NEF 1225, for example, a NEF that is positioned at a moresuitable location along a mobility path. The SMF 1223 subsequentlytransmits 1202 a NEF relocation request to the source NEF 1224. Thesource NEF 1224 transmits 1203 a UE group context transfer to the targetNEF 1225 and the target NEF 1225 transmits 1204 an acknowledgement ofsame to the source NEF 1224. The source NEF 1224 subsequently transmits1205 an update NEF request to the AF 1226 and the AF 1226 subsequentlytransmits 1206 a response to same to the source NEF 1224. The source NEF1224 transmits 1207 an update UE group context request to the UDM 1221.The UDM 1212 transmits 1208 a UE group context modification request tothe PCF 1220 and subsequently receives 1209 a response to same from thePCF 1220. The UDM 1221 transmits 1210 a UE group context modificationrequest to the AMF 1222 and subsequently receives 1211 a response tosame from the AMF 1222. In addition, the UDM 1221 transmits 1212 anupdate UE group context response to the source NEF 1224 and the sourceNEF 1224 subsequently transmits 1213 a NEF relocation response to theSMF 1223. It is noted that as the source NEF has already sent a UE groupcontext transfer to the target NEF, the AF, SMF, PCF and AMF do not needto correspond with the target NEF as the target NEF has already beadvised of this transfer.

Having further regard to FIG. 12, while it is illustrated that the UDMtransmits UE group context modification requests to the PCF and the AMF,it will be readily understood that the source NEF can transmit one of orboth of these UE group modification requests instead and subsequentlyreceive the corresponding response.

In current V2X platooning solutions, for example when plural UEs aretravelling in the same vehicle, the application server selects aparticular UE to be a leader for the plurality of UEs in the vehicle. Inthis configuration, the UE leader receives messages on behalf of theplurality of UEs and the UE leader forwards these messages to theplurality of UEs using device to device (D2D) links, for example PC5side link in LTE. According to embodiments, when the plurality of UEshave been assigned to a UE group, the application server (AS) is capableof communicating with each of the UEs within the UE group directly.However, for a handover situation, for example is the UE group isdefined to include a plurality of UEs travelling in the same vehicle,the handover can be performed by a transfer of the UE group context froma source RAN to a target RAN. In this embodiment, in the RAN or AN, allindividual UEs are handed over to the target RAN (T-RAN), wherein thesource RAN (S-RAN) transfers the UE group context to the T-RAN and theT-RAN requests a path switch for all UEs by using the UE group context,which may identify shared PDU sessions or non-shared PDU sessions orboth. Upon the path switch, the communication for all of the UEs in theUE group will pass through the T-RAN. Since all of the UEs of the UEgroup may access the same data network (DN), the handover delayassociated with the transfer of all of the UEs by transferring the UEgroup context, when compared to the handover of each of the UEsindividually, would be essentially the same or less. However, it will bereadily understood that the required signalling overhead that would berequired to handover all of the UEs of the group, would be significantlyreduced when transferring the UE group context rather than transferringeach UE individually.

FIG. 13 illustrates a situation wherein there is a single UE in the UEgroup, according to embodiments of the present invention. The UE 1310 inthe vehicle is moving, from an area served by a S-(R)AN 1301 to anotherarea served by T-(R)AN 1302. During the movement, the UE 1310 may beserved by different SMF, Source SMF (S-SMF) 1304 and Target SMF (T-SMF)1305, and UPF, Source UPF (S-UPF) 1306 to Target UPF (T-UPF) 1307. TheT-SMF 1305 may select the T-UPF 1307 to connect the UP path between theT-(R)AN 1302 and the Target DNAI (T-DNAI) 1308. The S-DNAI 1311 providesUP access to the Application Server 1, or Source AS (S-AS) 1312. TheT-DNAI 1308 provides UP access to the Application Server 2, or Target AS(T-AS) 1309. The operation of ASs is coordinated by a mobile edgecomputing (MEC) orchestrator 1340. The MEC Orchestrator 1340 mayexchange control messages with the CN 1315 via AFs, such as Source AF(S-AF) 1320 and Target AF (T-AF) 1321. Each AF may be configured by theMEC Orchestrator 1340 to interact with certain NEFs, for example theS-AF 1320 interacts with S-NEF 1313 and T-AF 1321 interacts with T-NEF1314.

According to embodiments, the application servers and AFs can be part ofthe mobile edge computing (MEC) platform. The AF is the sound-boundinterface, providing control link to the CN of mobile network. The DNAIrepresents an access point to the user plane of the application in theMEC platform. There can be multiple local ASs that are geographicallyclose to the UE location. The AF may support one or multiple ASs. TheNEF may be configured to be associated with one or multiple AFs, and/orassociated with one or multiple DNAIs, and/or associated with one ormultiple applications, and/or associated with one of multiple DNNs,and/or associated with one or multiple UE groups, and/or associated withone or multiple geographical zone IDs, and/or associated with one ormultiple UPFs, and/or associated with one or multiple registrationareas, and/or associated with one or multiple LADNs, and/or associatedwith one or multiple AMFs, and/or associated with one or multiple SMFs,and/or associated with one or multiple PCFs, and/or associated with oneor multiple UDSF (unstructured data storage function), and/or associatedwith one or multiple UDM functions, and/or associated with one ormultiple UDR functions.

According to the scenario as shown in FIG. 13, a NEF such as the T-NEF1314 may be selected by an AF such as the T-AF 1321 based on obtainedinformation. FIG. 14 can be taken as an example. In the method, the T-AF1450 may obtain the information related to the UE in various ways, e.g.,by communicating with one or more function such as the S-AF 1460. Basedon the information related to the UE, the T-AF 1450 may replace the S-AF1460 in the subscription of event exposure services of the S-NEF 1420and in the transmission of an AF request related to influence on trafficrouting, for example through a procedure including steps 1402 to 1405.To perform the selection of the T-NEF 1430 such as step 1406, the T-AF1450 may obtain the information of the NEF in various way, for example,a CAPIF (common API framework) function 1440, the NRF, or the CP NFssuch as AMF and SMF which locally store the NEF information. Theselected T-NEF 1430 will replace the S-NEF 1420 to cooperate with theT-AF 1450 further, e.g., in the subscription of event exposure servicesor in the transmission of an AF request related to influence on trafficrouting or both, for example through a procedure including steps 1407 to1410. FIG. 14 shows a method of selecting or re-selecting an NEF inaccordance with embodiments of the present invention. The NEF is used toexchange the CP messages between the CN CP functions and the AF, such asmessages relating to requests to influence traffic routing, or messagesrelating to subscribing to event exposure service. The NEF may be alsoused to transfer the data packets between the UE and the AF or the AS.The method in FIG. 14 may be applied to individual UEs or UE groups. Forexample, when applied to individual UEs, the AF can obtain UE contextsand when applied to a UE group, the AF can obtain the UE group context.

In step 1401, the S-AF 1460 transfers the UE context to the T-AF 1450.The UE context stored in the AF contains all the information related tothe UE, such as external UE ID, external group ID, GPSI, S-NSSAI, S-NEFID, UE location information, current subscribed services in the NEFs,such as the S-NEF 1420, transaction ID(s) that represent AF-influencerequests sent to the S-NEF 1420. It will be understood, that in someinstances, step 1401 includes the transfer of UE group context.

In a case of UE group context, the UE group context may include the UEIDs that are in the UE group, the UE that is the leader (or groupmaster, or group head), the location of all UEs of the UE group. Forexample, UE group context can include one or more of UE groupidentifier, one or more protocol data unit (PDU) session contexts, andtheir PDU session identifiers, one or more shared protocol data unit(PDU) session context and their identifiers and a list of UE IDs whichare members of the UE group.

In step 1402, the T-AF 1450 may subscribe to event exposure services ofthe S-NEF 1420, e.g., as described in 3GPP TS 23.502, 4.15.3.2.3, and byusing Nnef_EventExposure_Subscribe service in clause 5.2.6.2.2, for theUE or UEs in the UE group.

In step 1403, the T-AF 1450 may send the influence traffic routingrequest to the S-NEF 1420, e.g., as described in 3GPP TS 23.502, clause4.3.6.2, and by using Npcf_PolicyAuthorization_Create service in clauses5.2.5.3.2, for the UE or UEs in the UE group.

In step 1404, the S-AF 1460 may un-subscribe event exposure services ofS-NEF 1420, e.g., as described in 3GPP TS 23.502, clause 5.2.6.2.3 byusing Nnef_EventExposure_Delete service, for the UE or UEs in the UEgroup.

In step 1405, the S-AF 1460 may cancel AF-influence traffic routingrequest in the S-NEF 1420, e.g., as described in 3GPP TS 23.502, clause5.2.5.3.4 by using Npcf_PolicyAuthorization_Delete service, for the UEor UEs in the UE group.

In step 1406, the T-AF 1450 may decide to select a new NEF. Theinformation of NEF may be stored in a CAPIF (common API framework) corefunction 1440. The NEF may provide its configuration information to theCAPIF core function by using a procedure, e.g., as described in clause8.3 Publish Service API of 3GPP TS 23.222, published in January 2018.The NEF may be configured to serve the whole PLMN network, or some partsof PLMN for example. The NEF may be selected based on the one or more ofthe following information: PLMN ID, DNN, DNAI(s); applications,represented by application ID(s), AF-Service-Identifier; some networkslice instances, represented by S-NSSAI, or NSI-ID (network sliceinstance ID); UE group ID(s), such as internal group ID, external groupID, IMSI group ID; UE ID(s); AF, such as AF ID, AF IP address, AF FQDN;UPF address (UPF IP address or FQDN); AMF, such as AMF ID, AMF IPaddress, AMF FQDN; SMF, such as SMF ID, SMF IP address, SMF FQDN. Forexample, the T-AF 1450 decides to select a new NEF based on thefollowing conditions which can include: PLMN=101, DNN=“Internet”,AF-Service-Identifier=“V2X Application-1”, S-NSSAI=100. Assuming thatthe T-NEF 1430 is configured to serve V2X, where PLMN=101,DNN=“Internet”, AF-Service-Identifier=“V2X Application-1”, S-NSSAI=100,the T-NEF 1430 is the new NEF that is selected by the T-AF 1450.

The NEF configuration information can also be stored in the NRF, orlocally stored in the CP NFs such as AMF and SMF.

In step 1407, after selecting a T-NEF 1430, the T-AF 1450 may subscribeto event exposure Services of T-NEF 1430, e.g., as described TS 23.502,clause 4.15.3.2.3, and by using Nnef_EventExposure_Subscribe service inclause 5.2.6.2.2.

In step 1408, the T-AF 1450 may send Influence traffic routing requeststo the T-NEF 1430, e.g., as described in 3GPP TS 23.502, clause 4.3.6.2,and by using Npcf_PolicyAuthorization_Create service in clauses5.2.5.3.2.

In step 1409, the T-AF 1450 may un-subscribe to event exposure servicesof the S-NEF 1420, e.g., as described in 3GPP TS 23.502, clause5.2.6.2.3 Nnef_EventExposure_Delete service.

In step 1410, the T-AF 1450 may cancel AF-influence traffic routingrequests in the S-NEF 1420, e.g., as described in TS 23.502, clause5.2.5.3.4 by using Npcf_PolicyAuthorization_Delete service.

In steps 1402 to 1405, 1407 to 1410, the S-NEF 1420 and T-NEF 1430 mayneed to perform subscription or unsubscription for network exposureservices of CP functions 1410 such as UDM, AMF, SMF, PCF.

According to embodiments, the above procedure allows a T-AF 1450 tosubscribe to the current serving S-NEF 1430.

In some embodiments, the T-AF 1450 may not need to subscribe or sendrequests to the S-NEF 1420. In this case steps 1402 and 1403 areskipped. The T-AF 1450 subscribes for the event exposure services of theT-NEF 1430 in steps 1404 and 1405. In this case, steps 1409 and 1410 arealso skipped.

In some embodiments, the same AF can serve both application servers(S-AS and T-AS). The S-AF 1460 does not need to perform transfer the UEcontext information to the T-AF 1450. Steps 1401 to 1405 are skipped.Steps 1406 to 1410 are performed with the T-AF is replaced by S-AF sincethere the S-AF and T-AF are the same.

FIG. 15 illustrate another NEF re-selection embodiment, where a controlplane network function, such as SMF, may trigger the re-selection ofNEF. The procedure may include the following steps.

In step 1501, a number of triggers could require a re-selection of NEF.For example a trigger can be a result of one or more of: UE mobilityevent, when UE moves to new location that is served by a new (R)AN node,during the handover procedure, the SMF 1540 is notified by the AMF 1530about new UE location; application mobility event, where the applicationserver (AS) may be relocated to a new data centres or to anothercomputing machine in the same data centre, the AF may send AF-influencetraffic routing to the SMF 1540 via the PCF 1510; and load balancingamong NEF, maintenance, relocation of S-NEF in data centres, denial ofservice (DoS) attack, a network management function, such as Operation,Administration, and Management (OAM) function may inform the SMF 1540.For example, if the current NEF is highly loaded, the NEF may inform aCP NF, such as SMF, to request NEF re-selection.

In step 1502, a CP NF, such as SMF 1540 decides to select another NEF toserve the UE or the PDU Session of the UE based on triggers from step1501. The SMF may interact with the NRF or a CAPIF Core function toidentify a suitable NEF. The CP, such as SMF, may provide one or more ofthe following information to the NRF or CAPIF Core function: mobilenetwork information, such as PLMN ID, DNN; network slice information,represented by e.g. S-NSSAI, or NSI-ID; application information, such asAF-service-identifier, application ID, external application ID, internalapplication ID, DNAI information (e.g. DNAI ID); UE information, such asinternal group ID, IMSI group ID, external group ID, UE ID (e.g. SUPI,GPSI); UE location information, such as serving (R)AN node ID, (R)AN IPaddress or FQDN; CP network function information of serving AMF, SMF,PCF, UDM information (e.g. network function ID, or, IP Address, orFQDN); and UPF information, for example the UPF ID, or its IP address orFQDN.

In some embodiments, the S-NEF 1550 may initiate the NEF reselectionitself. In this method, in step 1502, the S-NEF 1550 may directlyinteract with the NRF or CAPIF Core function to identify a T-NEF. An NEFmay have locally stored information to select another NEF.

In some embodiments, the NRF or CAPIF Core function may provide the listof possible NEFs that could serve the UE or the PDU session, togetherwith attributes of the NEFs to the requested CP NF. The attributes ofthe NEF could include one or more of the following information: mobilenetwork information, such as PLMN ID, DNN; network slice information,represented by e.g. S-NSSAI, or NSI-ID; application information, such asAF-service-identifier, application ID, external application ID, internalapplication ID, DNAI information (e.g. DNAI ID); UE information, such asinternal group ID, IMSI group ID, external group ID, UE ID (e.g. SUPI,GPSI); UE location information, such as serving (R)AN node ID, (R)AN IPaddress or FQDN; CP network function information of serving AMF, SMF,PCF, UDM information (e.g. network function ID, or, IP address, orFQDN); and UPF information: the UPF ID, or its IP address or FQDN. TheNRF or CAPIF Core function may return the list of NEFs that match theinformation provided by the SMF 1540, and optionally, the loadinformation of the NEFs. The load information could be the percentage ofresources of NEF are being used.

In step 1503, if a CP NF, such as SMF 1540, sends to the S-NEF a requestfor a NEF relocation, e.g., a NEF relocation request. The request mayinclude one or more of the following: CP NF ID (such as SMF ID, SMF IPaddress or FQDN); the information of the T-NEF 1560 (such as T-NEF ID,or IP address, or FQDN); the time to start NEF relocation (immediate orscheduled time and date); the information to identify the UE: SUPI,GPSI, and/or internal group ID, or an internal transaction ID associatedwith a previous request from the AF 1570; the information to identifyPDU session of the UE, such as packet flow description (PFD); locationinformation: e.g. geographical zone IDs; and the information to identifyapplication: e.g. application ID, AF-service-identifier, DNAI.

In some embodiments, all the operation of the S-NEF 1550 may betransferred to the T-NEF 1560. In step 1503, the CP function, such asSMF 1540, may provide CP NF ID (such as SMF ID, SMF IP address or FQDN);the information of the T-NEF 1560 (such as T-NEF ID, or IP address, orFQDN); the time to start NEF relocation (immediate or scheduled time anddate) to the S-NEF 1550.

According to some embodiments, the CP NF, such as SMF 1540, may use aservice of NEF, namely Nnef_UEContext_Relocation service described inthe present application, to send the NEF Relocation Request.

In step 1504, the S-NEF 1550 sends to the T-NEF 1560 a request fortransferring UE context, e.g. UE context (or UE group context) transferrequest. The request may include the one or more of the followinginformation: the S-NEF ID; time to start NEF re-selection: immediate orat a scheduled time; the UE context information, which can include UErelated information, AF related information, information on subscribedservices of CP NFs and information on user plane. According toembodiments, UE related information can include one or more of UE ID(SUPI, GPSI, IP address/prefix); parameter mapping of SUPI to GPSI;external group ID; mapping of external Group ID and IMSI-Group ID.According to embodiments, AF related information can include one or moreof AF-Service-Identifier (for example edge computing applications);whether the AF is authorized or not; parameter mapping ofAF-service-identifier and 5GC information (DNN, S-NSSAI) (for exampleedge computing applications); parameter mapping of AF-service-identifierand a list of DNAI(s) and routing profile ID(s) (edge computing);parameter mapping of external application identifier to thecorresponding application identifier known at the PFDF (PFD management);AF request: mapping of AF transaction internal ID and AF transaction IDin the AF request (edge computing); AF subscription for event monitoring(for example event exposure services of CN): “NEF records theassociation of the event trigger and the requester identity.”; and Quotaor Rate of Trigger Submission (for example SMS over NAS applications).According to embodiments, information on subscribed services of CP NFscan include one or more of CP NF IDs that the S-NEF subscribed theirservices: SMF ID, PCF ID, UDM ID, AMF ID, and others; the NEF stores AFnotification reporting information received from the AF and maps it toNEF notification reporting information intended for PCF(s) (for exampleedge computing applications); PCF subscription for NEF notificationabout AF request (for example in edge computing applications); eventsubscription of NEF for monitoring event exposure; event filters (forexample bulk subscription services); AMF events, including bulksubscription for many UEs (for example event exposure service); and UDMevents (for example event exposure services). According to embodiments,information on the user plane can include one or more of the UPF thatprovides UP connection for IoT messages transfer between the AF/AS tothe UE and PDU session context of the UE that use the S-NEF forcommunication with the AF or AS.

According to some embodiments the S-NEF 1550 may use theNnef_UEContext_Create described in the present document to send the UEinformation from the S-NEF 1550 to the T-NEF 1560.

According to some embodiments, the NEF may store the UE context in alocal storage media. Alternatively, the NEF may store the UE context inan external storage function such as UDSF (unstructured data storagefunction), UDR. If the UE context is stored in an external storagefunction, the S-NEF 1550 retrieves the UE context from the storagefunction and sends to the T-NEF 1560. Alternatively, the S-NEF 1550 mayinform the T-NEF 1560 the location of the UE context, which may includethe network storage function address or ID (e.g. UDSF IP address, UDSFID, UDR ID, UDR IP address), the UE information (UE ID (GPSI, SUPI,external UE identifier)). In case of UE group, the S-NEF 1550 mayinclude the internal group ID, or external group ID.

According to some embodiments the S-NEF 1550 may also notify the CPfunction, such as UDM, SMF, AMF, and PCF the location of UE context ofNEF. This step is not shown in FIG. 15. In case a DoS attack happens tothe S-NEF 1550, the SMF 1540 may directly send a NEF relocation requestto the T-NEF 1560. This request may include the storage location of NEFUE context for the T-NEF 1560 to retrieve. In some scenarios, e.g. a DoSattack scenario, NEF failure, and some other scenarios, steps 1504,1512, 1513, 1514, 1515 may be skipped.

According to embodiments, subsequently, the T-NEF 1560 may subscribe tothe services of CP NFs.

In step 1505, the T-NEF 1560 may subscribe to the event exposure serviceof the SMF 1540, e.g., by using “Nsmf_EventExposure_Subscribe” service,as described in 3GPP TS 23.502, clause 5.2.8.3.

In step 1506, the T-NEF 1560 may subscribe to the event exposure serviceof the AMF 1530, e.g., by using “Namf_EventExposure_Subscribe” service,as described in 3GPP TS 23.502, clause 5.2.2.3.

In step 1507, the T-NEF 1560 may subscribe to the event exposure serviceof the UDM 1520, e.g., by using “Nudm_EventExposure_Subscribe” service,as described in 3GPP TS 23.502, clause 5.2.3.5.

In step 1508, the T-NEF 1560 may subscribe to the event exposure serviceof the PCF 1510, e.g., by using “Npcf_Policy Authorization_Subscribe”service, as described in 3GPP TS 23.502, clause 5.2.5.3.

In step 1509, after completing all subscription services, the T-NEF 1560sends to the S-NEF 1550, e.g. the UE context (or UE group context)transfer response, to confirm that the T-NEF is ready to serve the AF1570. The T-NEF 1550 may use the Nnef_UEContext_Create described in thepresent document to send the UE Context Transfer Response from the T-NEF1560 to the T-NEF 1550.

In step 1510 a, the S-NEF 1550 may send a message to request the AFupdating the NEF information, e.g. update NEF request, to the AF 1570 sothat the AF 1570 will communicate with the new T-NEF 1560. The messagemay include an identifier of T-NEF 1560, such as IP address, or NEF IDand a cause code indicating the reason to change the NEF.

In step 1510 b, the AF 1570 may send an acknowledgment, e.g. update NEFresponse, to the S-NEF 1550 to confirm the reception of the new NEFinformation. The AF 1570 use the T-NEF 1560 for communication with theCN NFs. If the S-NEF 1550 receives any notification messages from otherCP functions related to the UE or PDU session that has been transferredto the T-NEF 1560, the S-NEF 1550 will not forward these messages to theAF 1570. This is to avoid forwarding the same notification messages fromthe S-NEF 1550 and the T-NEF 1560 to the AF 1570.

In some embodiments, steps 1510 a and 1510 b can be implemented by usinga service of AF, namely Naf_UEContext_Update, described in the presentdocument.

In case of a DoS attach, NEF failure or maintenance, or some otherscenarios, the T-NEF 1560, instead of S-NEF 1550, sends message in step1510 a to the AF. The message may include identifiers of S-NEF and T-NEF1560, such as IP addresses, or NEF IDs, a cause code indicating thereason to change the NEF (e.g. DoS attack, NEF failure, NEF maintenance,load balancing, better packet delay), and transaction ID(s) that the AF1570 has used to send AF-influence traffic routing requests to the CNpreviously. In this case, the AF 1570 sends an update NEF response tothe T-NEF 1560, instead to the S-NEF 1550.

In step 1511, the S-NEF 1550 may send a message to, e.g. NEF RelocationResponse to the CP, such as SMF. This is to confirm that the newlyselected T-NEF 1560 is ready for exchanging CP messages or UP datapackets with the AF 1570 or the application server.

According to some embodiments, the S-NEF 1550 may use a service of NEF,namely Nnef_UEContext_Relocation service described in the presentapplication, to send the NEF relocation response to the SMF 1540.

Subsequently, the S-NEF 1550 may unsubscribe the services of CP NFs.

In step 1512, the T-NEF 1560 may unsubscribe to the event exposureservice of the SMF 1540, by using “Nsmf_EventExposure_UnSubscribe”service, e.g. as described in 3GPP TS 23.502, clause 5.2.8.3.

In step 1513, the S-NEF 1560 may unsubscribe to the event exposureservice of the AMF 1530, by using “Namf_EventExposure_UnSubscribe”service, e.g. as described in 3GPP TS 23.502, clause 5.2.2.3.

In step 1514, the T-NEF 1560 may unsubscribe to the event exposureservice of the UDM 1520, by using “Nudm_EventExposure_UnSubscribe”service, e.g. as described in 3GPP TS 23.502, clause 5.2.3.5.

In step 1515, the T-NEF 1560 may unsubscribe to the event exposureservice of the PCF 1510, “Npcf_Policy Authorization_UnSubscribe”service, e.g. as described in 3GPP TS 23.502, clause 5.2.5.3.

In FIG. 14 and FIG. 15, the UE context may be transfer or updated in theAF. By using a service-based interface, the AF can provide the followingservices to support UE context transfer and update between two AFfunctions. Services of the AF related to UE context (e.g. could be namedas Naf_UEContext) may include UE context creation (e.g. could be namedNaf_UEContext_Create), UE context update (e,g, which could be namedNaf_UEContext_Update), UE context release in AF (e.g. which could benamed Naf_UEContext_Release) and get UE context from an AF (e.g. whichcould be named Naf_UEContext_Get).

According to embodiments, UE context creation enables the creation of anew UE context in the AF. The required input can include UE ID (e.g.GPSI, IMSI). Optional input can include one or more of UE locationinformation, subscription get notified of PDU session status change,PEI, GPSI, AN type, NEF ID, UE related information (UE ID (SUPI, GPSI,IP address(es)/prefix(es))), whether the AF is authorized or not,transaction IDs (each corresponds to one AF request), AF Subscriptionfor Event Monitoring (event exposure), information on subscribedservices of CP NFs; CP NF IDs that the S-NEF subscribed their services:SMF ID, PCF ID, UDM ID, AMF ID, and others and event filters (for bulksubscription). The required output from UE context creation function isa result indication, for example success or not success, and in someembodiments an optional output can be a cause.

According to embodiments, the UE context update function can enable theupdating of an existing UE context in the AF. The input can include UEID (e.g. GPSI, IMSI). The input can optionally include one or more of UElocation information, subscription get notified of PDU session statuschange, PEI, GPSI, AN type, NEF ID, UE related information (UE ID (SUPI,GPSI, IP address(es)/prefix(es))), whether the AF is authorized or not,transaction IDs (each corresponds to one AF request), AF subscriptionfor event monitoring (event exposure), information on subscribedservices of CP NFs; CP NF IDs that the S-NEF subscribed their services:SMF ID, PCF ID, UDM ID, AMF ID, and others; and event filters (bulksubscription). The required output from UE context update function is aresult indication, for example success or not success, and in someembodiments an optional output can be a cause or external UE ID or both.

According to embodiments, the UE context release in AF function canrelease an existing UE context in the AF. The required input can includeUE ID (e.g. GPSI, IMSI, external UE ID). The required output from UEcontext release function is a result indication, for example success ornot success, and in some embodiments an optional output can be a causeor external UE ID or both.

According to embodiments, the get UE context from AF function can enablea consumer function to get the UE context in an AF. The required inputcan include UE ID (e.g. GPSI, IMSI). The required output from the get UEcontext from AF function is a result indication, for example success ornot success, and UE context stored in AF. In some embodiments anoptional output can be a cause (e.g. UE context does not exist, UEcontext is not allowed to be transferred out of AF, UE ID (e.g. externalUE ID, GPSI).

According to embodiment, services of the NEF related to UE context(e.g., the name of the service could be Nnef_UEContext) include UEcontext creation in NEF (e.g. which could be namedNnef_UEContext_Create), UE context update in NEF (e.g. which could benamed Nnef_UEContext_Update), UE context release in NEF (e.g. whichcould be named Nnef_UEContext_Release), UE context relocation (e.g.which could be named Nnef_UEContext_Relocation) and get UE context froman NEF (e.g. which could be named Nnef_UEContext_Get).

According to embodiments the UE context creation in NEF function cancreate a new UE context in the NEF. The required input can include UE ID(e.g. SUPI, GPSI, IMSI, 5G-GUTI). Optional input can include one or moreof: UE related information: IP address/prefix, UE location (e.g. RANaddress) parameter mapping of SUPI to GPSI, internal-group ID, externalgroup ID, mapping of external group ID and IMSI-group ID, mapping ofexternal group ID and internal-group ID, packet flow description (PFD);AF related information: AF-service-identifier, whether the AF isauthorized or not, parameter mapping of AF-service-identifier and 5GCinformation (DNN, S-NSSAI), parameter mapping of AF-service-identifierand a list of DNAI(s) and routing profile ID(s), parameter mapping ofexternal application identifier to the corresponding applicationidentifier known at the PFDF (PFD management); AF request: mapping of AFtransaction internal ID and AF transaction ID in the AF request (edgecomputing); AF subscription for event monitoring (event exposure): “NEFrecords the association of the event trigger and the requesteridentity.”; quota or rate of trigger submission (SMS over NAS);information on subscribed services of CP NFs; information on user planeand PDU session context of the UE that use the S-NEF for communicationwith the AF or AS. According to embodiments, information on subscribedservices of CP NFs can include one or more of CP NF IDs that the S-NEFsubscribed their services: SMF ID, PCF ID, UDM ID, AMF ID, and others;the NEF stores AF notification reporting information received from theAF and maps it to NEF notification reporting information intended forPCF(s) (edge computing); PCF subscription for NEF notification about AFrequest (edge computing); event subscription of NEF for monitoring eventexposure; event filters (bulk subscription); AMF events, including bulksubscription for many UEs (event exposure); and UDM events (eventexposure). According to embodiments, information on the user plane caninclude the UPF that provides UP connection for IoT messages transferbetween the AF/AS to the UE. The required output from the UE contextcreation in NEF function is a result indication, for example success ornot success, and in some embodiments an optional output can be a cause.

According to embodiment, the UE context update in NEF function canupdate an existing UE context in the NEF. The required input can includeUE ID (e.g. GPSI, IMSI). Optional input can include one or more of UErelated information: IP address/prefix, UE location (e.g. RAN address),parameter mapping of SUPI to GPSI, external group ID, mapping ofexternal group ID and IMSI-group ID, packet flow description (PFD); AFrelated information: AF-service-identifier, whether the AF is authorizedor not, parameter mapping of AF-service-identifier and 5GC information(DNN, S-NSSAI), parameter mapping of AF-service-identifier and a list ofDNAI(s) and routing profile ID(s), parameter mapping of externalapplication identifier to the corresponding application identifier knownat the PFDF (PFD management); AF request: mapping of AF transactioninternal ID and AF transaction ID in the AF request (edge computing); AFsubscription for event monitoring (event exposure): “NEF records theassociation of the event trigger and the requester identity.”; quota orrate of trigger submission (SMS over NAS); information on subscribedservices of CP NFs; information on user plane and PDU session context ofthe UE that use the S-NEF for communication with the AF or AS. Accordingto embodiments, information on subscribed services of CP NFs can includeone or more of CP NF IDs that the S-NEF subscribed their services: SMFID, PCF ID, UDM ID, AMF ID, and others; The NEF stores AF notificationreporting information received from the AF and maps it to NEFnotification reporting information intended for PCF(s) (edge computing);PCF subscription for NEF notification about AF request (edge computing);event subscription of NEF for monitoring event exposure; event filters(bulk subscription); AMF events, including bulk subscription for manyUEs (Event Exposure); and UDM events (Event Exposure). According toembodiments, information on the user plane can include the UPF thatprovides UP connection for IoT messages transfer between the AF/AS tothe UE. The required output from the UE context creation in NEF functionis a result indication, for example success or not success, and in someembodiments an optional output can be a cause.

According to embodiments, the UE context release in NEF function canrelease an exiting UE context in the NEF. The required input may includeone or more of the following information: UE ID (e.g. SUPI, GPSI, IMSI),internal group ID, external group ID, AF-service-identifier, networkslice information (e.g. S-NSSAI, or NSI ID), location information (e.g.geographical zone IDs), CP function information (e.g. PCF ID, SMF ID).The required output from UE context release in NEF function is a resultindication, for example success or not success, and in some embodimentsan optional output can be a cause or external UE ID or both.

According to embodiments, the UE context relocation function can enablea consumer function to request relocation of an existing UE context inthe NEF to another NEF. The required input may include one or more offollowing information:information to identify CP NF requesting UEcontext relocation (such as SMF ID, SMF IP address or FQDN); theinformation of the T-NEF 1560 (such as T-NEF ID, or IP address, orFQDN); the time to start NEF relocation (immediate or scheduled time anddate); information to identify network slice, e.g. S-NSSAI, NSI-ID; theinformation to identify the UE, e.g. one or more of SUPI, GPSI, internalgroup ID, and external group ID, IMSI group ID; information to identifyAF request, e.g. an internal transaction ID associated with a previousrequest from the AF 1570; the information to identify PDU session of theUE, such as packet flow description (PFD); location information (e.g.geographical zone IDs, UPF serving area, registration area, LADN servicearea, SMF service area, AMF service area); and the information toidentify application (e.g. DNN, application ID, AF-service-identifier,DNAI). The input may optionally include a cause (e.g. maintenance, DoSattack, load balancing). The required output from UE context relocationfunction is a result indication, for example success or not success, andin some embodiments an optional output can include a cause (e.g. UEcontext does not exist, UE context is not allowed to be relocated). Forexample, if one UE context is to be relocated, the consumer function mayprovide the UE ID. If UE contexts of all UEs of one UE group is to betransferred, the consumer function may provide the internal group ID. Ifthe UE context of all UEs using an application, the consumer functionmay provide the AF-service-identifier, or application ID.

According to embodiments, the get UE context from an NEF function canenable a consumer function to get UE context in an NEF. The requiredinput can include one or more of the following information: informationto identify CP NF requesting UE context relocation (such as SMF ID, SMFIP address or FQDN); information to identify network slice, e.g.S-NSSAI, NSI-ID; the information to identify the UE, e.g. one or more ofSUPI, GPSI, internal group ID, external group ID and IMSI group ID;information to identify AF request, e.g. an internal transaction IDassociated with a previous request from the AF 1570; information toidentify PDU session of the UE, such as packet flow description (PFD);location information (e.g. geographical zone IDs, UPF serving area,registration area, LADN service area, SMF service area, AMF servicearea); and information to identify application (e.g. DNN, applicationID, AF-service-identifier, DNAI). The optional input can include acause. The required output from get UE context from an NEF function is aresult indication, for example success or not success and the UE contextstored in the NEF. In some embodiments an optional output can be a cause(e.g. UE context does not exist, UE context is not allowed to betransferred out of NEF), UE ID (e.g. SUPI, GPSI).

The NEF may provide a relocation service to other functions. Thisservice may be named Nnef_Relocation. A consumer function may request toreplace a source NEF by another target NEF. The target NEF get all theUE context data from the source NEF or a separate storage function, e.g.the UDR or UDSF. The consumer function may send to the target NEF one ormore of the following information: the source NEF ID (or IP address,FQDN); UE information e.g. UE ID (e.g. SUPI, GPSI, internal Group ID,external group ID); storage function information (e.g. source NEF ID,source NEF IP address, UDR ID, or UDR IP address, UDSF IP, UDSF IPaddress); cause (e.g. maintenance, DoS attack, load balancing). Thetarget may send to the consumer function the result, which may includeone or more of the following information: result indication (success,not success); cause (e.g. UDR data query error). To fulfil the NEFrelocation request, the target NEF may access all the UE context datafrom the provided source that keeps the UE context data, such as sourceNEF or a storage function. More details in this regard are explained inFIG. 16 as an example.

The CAPIF core function can provide notifications for CAPIF events. TheCAPIF events may be an NEF instance is out of service (e.g. due tonetwork maintenance, hardware error, software error, DoS attack), an NEFinstance is added, an NEF is replaced by another NEF.

The AF can subscribe for CAPIF event notifications. When subscribing forCAPIF event, the AF may provide its AF ID an event filter, which mayinclude the PLMN ID, DNN, LADN, network slice information (such asS-NSSAI, NSI-ID), UE group (such as external group ID), applicationinformation (such as AF-service-ID, application ID), locationinformation (such as geographical zone ID), UE information (such asGPSI, external UE ID, IMSI), NEF information (such as NEF ID, or APIID). The CAPIF shall send CAPIF notifications to the subscribed AF whenthe conditions of CAPIF events are matched with the event filter.

The NEF UE context of certain services, such as URLLC, may be stored ina separate storage function such as UDSF. The NEF, which is in charge ofsupport UE connection may inform the CAPIF core function the location ofthe NEF UE Context, such as the ID, IP address, or FQDN of the UDSF. Ifone NEF instance is out of service for some reason, the CAPIF, or AF mayselect another the UE. The CAPIF can provide newly selected NEF instancewith the location of the UE context so that the newly selected NEF isready to fulfill the AF requests without any interruption.

FIG. 16 illustrates a method to relocate an NEF in accordance withembodiments of the present invention.

In step 1601, the S-NEF 1650 stores the UE context, PDU session contextor both in the UDR 1645, e.g., by using services of UDR 1645. In the UEcontext, PDU session context or both, is created for the first time, aservice which may be called Nudr_UDM_Create, is used. If the UE context,PDU session context, or both is already created, the S-NEF 1650 may usea service which may be called Nudr_UDM_Update to update the UE context,PDU session context or both.

In step 1602, the CAPIF Core function 1665 decides to reselect anotherT-NEF 1660 to replace the S-NEF 1650. The S-NEF 1650 may need to bereselected in certain scenarios, for example DoS attack, NEF failure,NEF maintenance. In these scenarios, the network management function,such as Operation Administration Management (OAM) function, may informthe CAPIF Core function 1665 about the unavailability of the S-NEF 1650.Alternatively, the S-NEF 1650 may notify the CAPIF Core function aboutits status (e.g. DoS attack, NEF failure, NEF maintenance). This step isnot shown in FIG. 16.

The S-NEF 1650 may also notify the CAPIF Core Function 1665 about itsunavailability by sending a request which may be called “Service APIUnpublish” request e.g. as described in clause 8.4 of 3GPP TS 23.222,published in January 2018. This step is not shown in FIG. 16.

In step 1603, the CAPIF Core function 1665 may use NEF_Relocationservice to send relocation request to the T-NEF 1660.

In step 1604, the T-NEF 1660 may get the UE contexts if they are storedin a storage function, e.g., by using a service which may be calledNudr_UDM_Query service of the UDR 1645 to get the UE context, PDUsession context, or both previously stored by the S-NEF 1650.

In step 1605, the T-NEF 1650 may subscribe to the exposure eventnotification services of CP functions, such as PCF 1610, UDM 1620, AMF1630, or SMF 1640 for example as previously described with reference inFIG. 15.

In step 1606, the T-NEF 1650 may send a response, e.g. by usingNEF_Relocation Response to the CAPIF Core function 1665 for step 1603.

In step 1607 a, the CAPIF Core function 1665 may send a message, e.g.event notification, to the subscribed AF 1670 to inform theunavailability of the S-NEF 1650 and the information of replacementT-NEF 1660, such as the ID or IP address of the T-NEF 1660.

In step 1607 b, the AF 1670 may send a message, e.g. event notificationacknowledgement, to the CAPIF Core function 1665 to response the messagein step 1607 a.

In step 1608, the T-NEF 1660 may unsubscribe on behalf of the S-NEF 1650the exposure event notification services that the S-NEF 1650 subscribedto the CP functions, such as PCF 1610, UDM 1620, AMF 1630, or SMF 1640,previously.

In step 1609, alternatively, the S-NEF 1650 may unsubscribe the exposureevent notification services that the S-NEF 1650 subscribed to the CPfunctions, such as PCF 1610, UDM 1620, AMF 1630, or SMF 1640,previously.

The method as illustrated in FIG. 16 can have several advantages. Firstthe AF 1670 does not need to resend all the AF-influence traffic routingand subscription requests for network exposure event notificationservices in case the S-NEF 1650 is out of service. This would help toreduce the service interruption time that the CN CP functions and the AFcannot exchange control messages.

FIG. 17 is a block diagram of an electronic device (ED) 1701 illustratedwithin a computing and communications environment 1700 that may be usedfor implementing the devices and methods disclosed herein. In someembodiments, the electronic device may be an element of communicationsnetwork infrastructure, such as a base station (for example a NodeB, anevolved Node B (eNodeB, or eNB), a next generation NodeB (sometimesreferred to as a gNodeB or gNB), a home subscriber server (HSS), agateway (GW) such as a packet gateway (PGW) or a serving gateway (SGW)or various other nodes or functions within a core network (CN) or apublic land mobility network (PLMN). In other embodiments, theelectronic device may be a device that connects to the networkinfrastructure over a radio interface, such as a mobile phone, smartphone or other such device that may be classified as a User Equipment(UE). In some embodiments, ED 1701 may be a machine type communications(MTC) device (also referred to as a machine-to-machine (M2M) device), oranother such device that may be categorized as a UE despite notproviding a direct service to a user. In some references, an ED may alsobe referred to as a mobile device, a term intended to reflect devicesthat connect to mobile network, regardless of whether the device itselfis designed for, or capable of, mobility. Specific devices may utilizeall of the components shown or only a subset of the components, andlevels of integration may vary from device to device. Furthermore, adevice may contain multiple instances of a component, such as multipleprocessors, memories, transmitters, receivers, etc. The electronicdevice 1701 typically includes a processor 1702, such as a centralprocessing unit (CPU), and may further include specialized processorssuch as a graphics processing unit (GPU) or other such processor, amemory 1703, a network interface 1706 and a bus 1707 to connect thecomponents of ED 1701. ED 1301 may optionally also include componentssuch as a mass storage device 1704, a video adapter 1705, and an I/Ointerface 1708 (shown in dashed lines).

The memory 1703 may comprise any type of non-transitory system memory,readable by the processor 1702, such as static random access memory(SRAM), dynamic random access memory (DRAM), synchronous DRAM (SDRAM),read-only memory (ROM), or a combination thereof. In an embodiment, thememory 1703 may include more than one type of memory, such as ROM foruse at boot-up, and DRAM for program and data storage for use whileexecuting programs. The bus 1707 may be one or more of any type ofseveral bus architectures including a memory bus or memory controller, aperipheral bus, or a video bus.

The electronic device 1701 may also include one or more networkinterfaces 1706, which may include at least one of a wired networkinterface and a wireless network interface. As illustrated in FIG. 17,network interface 1706 may include a wired network interface to connectto a network 1712, and also may include a radio access network interface1711 for connecting to other devices over a radio link. When ED 1701 isa network infrastructure element, the radio access network interface1711 may be omitted for nodes or functions acting as elements of thePLMN other than those at the radio edge (e.g. an eNB). When ED 1701 isinfrastructure at the radio edge of a network, both wired and wirelessnetwork interfaces may be included. When ED 1701 is a wirelesslyconnected device, such as a User Equipment, radio access networkinterface 1711 may be present and it may be supplemented by otherwireless interfaces such as WiFi network interfaces. The networkinterfaces 1706 allow the electronic device 1701 to communicate withremote entities such as those connected to network 1712.

The mass storage 1704 may comprise any type of non-transitory storagedevice configured to store data, programs, and other information and tomake the data, programs, and other information accessible via the bus1707. The mass storage 1704 may comprise, for example, one or more of asolid state drive, hard disk drive, a magnetic disk drive, or an opticaldisk drive. In some embodiments, mass storage 1704 may be remote to theelectronic device 1701 and accessible through use of a network interfacesuch as interface 1706. In the illustrated embodiment, mass storage 1704is distinct from memory 1703 where it is included, and may generallyperform storage tasks compatible with higher latency, but may generallyprovide lesser or no volatility. In some embodiments, mass storage 1704may be integrated with a heterogeneous memory 1703.

The optional video adapter 1705 and the I/O interface 1708 (shown indashed lines) provide interfaces to couple the electronic device 1701 toexternal input and output devices. Examples of input and output devicesinclude a display 1709 coupled to the video adapter 1705 and an I/Odevice 1710 such as a touch-screen coupled to the I/O interface 1709.Other devices may be coupled to the electronic device 1701, andadditional or fewer interfaces may be utilized. For example, a serialinterface such as universal serial bus (USB) (not shown) may be used toprovide an interface for an external device. Those skilled in the artwill appreciate that in embodiments in which ED 1701 is part of a datacenter, I/O interface 1708 and Video Adapter 1705 may be virtualized andprovided through network interface 1706.

In some embodiments, electronic device 1701 may be a standalone device,while in other embodiments electronic device 1701 may be resident withina data center. A data center, as will be understood in the art, is acollection of computing resources (typically in the form of servers)that can be used as a collective computing and storage resource. Withina data center, a plurality of servers can be connected together toprovide a computing resource pool upon which virtualized entities can beinstantiated. Data centers can be interconnected with each other to formnetworks consisting of pools computing and storage resources connectedto each by connectivity resources. The connectivity resources may takethe form of physical connections such as Ethernet or opticalcommunications links, and in some instances may include wirelesscommunication channels as well. If two different data centers areconnected by a plurality of different communication channels, the linkscan be combined together using any of a number of techniques includingthe formation of link aggregation groups (LAGs). It should be understoodthat any or all of the computing, storage and connectivity resources(along with other resources within the network) can be divided betweendifferent sub-networks, in some cases in the form of a resource slice.If the resources across a number of connected data centers or othercollection of nodes are sliced, different network slices can be created.

According to embodiments, there is provided a method for managing userequipment (UE) in a communication network. The method includesreceiving, by a network function, a request from a UE, said UE belongingto a UE group and generating, by the network function, a UE groupcontext for the UE group.

According to some embodiments, the UE group context includes a UE groupidentifier. According to some embodiments, the UE group context includesone or more protocol data unit (PDU) session identifiers. According tosome embodiments, the UE group context includes one or more sharedprotocol data unit (PDU) session identifiers. According to someembodiments, the UE group context includes a list of UE IDs which aremembers of the UE group.

According to embodiments, there is provided a method for managing userequipment (UE) in a communication network. The includes receiving, by anetwork function, a request including data indicative of a UE group andtransmitting, by the network function, a notification, the notificationbased upon the request and the data.

According to some embodiments the data includes a UE group identifier.According to some embodiments, the data includes one or more protocoldata unit (PDU) session identifiers. According to some embodiments, thedata includes one or more shared protocol data unit (PDU) sessionidentifiers. According to some embodiments, the request includes arequest for modification of a shared PDU session and wherein thenotification includes a rejection. According to some embodiments, therequest includes a network exposure function (NEF) relocation requestand wherein the notification includes data indicative of a UE groupcontext and wherein the UE group context includes one or more of a UEgroup identifier, protocol data unit (PDU) session identifier and ashared PDU session identifier.

According to embodiments, there is provided a network function includinga network interface for receiving data from and transmitting data tonetwork functions connected to a network, a processor and anon-transient memory for storing instructions that when executed by theprocessor cause the network function to be configured to perform one ormore of the methods defined above.

According to embodiments, when the UE is moving, the V2X ApplicationServer may be relocated to meet the packet delay requirements. It isproposed to specify criteria for selecting the NEF to support domainmanagement and to minimize the delay of transferring the control andpossible data packets over the NEF.

Since the NEF is the interface for exchanging control messages betweenthe AF and CN network functions, it is important to make sure that theNEF is properly selected to minimize the delay of control messages andpossible data packets sent over the NEF. For example, in V2Xapplications, many control messages sent from AS/AF to the UE arelocation-dependent. If the location information of the UE is not quicklysent to the AF, the AF/AS may send incorrect control messages to the UE.Hence it is important to study existing mechanisms for NEF selection andidentify possible issues for improvements.

According to embodiments, a basic NEF selection solution mechanism isprovided. The AF can discover the NEF instances by using the CAPIFframework. In the SA WG2 meeting #125, SA WG2 agreed to support CAPIF.Therefore, it is assumed that the work of SA2 on NEF discovery in 5GCshall be carried in parallel.

This solution addresses Key Issue #8 (Support of edge computing). When avehicle travels a long distance, the V2X Application Server (V2X AS) maybe relocated along with the V2X UE in the vehicle to guarantee lowpacket delay requirements. FIG. 13 illustrates possible relocations ofthe network functions and V2X AS along with the UE's trajectory. The MECOrchestrator coordinates the operation of V2X ASs. The CP messagesbetween the MEC Orchestrator and the CN are exchanged via the AF andNEF. The NEF may be required as specified in clause 5.6.7 “ApplicationFunction influence on traffic”, TS 23.501 [7]. The UP connection betweenthe UE and V2X AS is provided by a (R)AN node, UPF, and DNAI. To supportthe UE mobility, the following steps can be carried out: 1) The movingUE is now served by a different RAN node, 2) The UPF and CP NFs may bere-selected, 3) The V2X AS may be relocated. The 5GC provides methodsfor the CN and the AF to negotiate the DNAI, 4) The NEF may be(re)selected.

Except for the NEF selection, other selection or reselection procedureshave been specified (for (R)AN, AMF, UPF, DNAI) or being studied (incase of SMF). The UE can be handed over between RAN nodes as describedin TS 23.502 [9], clause 4.9. The re-selection of UPF and DNAI have beenspecified in TS 23.501 [7], in clause 5.6.7 ‘Application Functioninfluence on traffic routing’ and clause 5.13 ‘Support for EdgeComputing’. The AMF may be re-allocated as described in TS 23.502 [9],clause 4.2.2.2.3 “Registration with AMF re-allocation”. The relocationof some CP functions can be separately studied. For example, therelocation of SMF and UP is being studied in Release 16 SID “Study onEnhancing Topology of SMF and UPF in 5G Networks” (ETSUN) [11].

Currently, the NEF selection is not explicitly specified in TS 23.501and TS 23.502. Anyway, according to the Common API Framework (CAPIF)[10] supported in 5GS, the AF can discover NEF instances by using CAPIFservices. Multiple NEF instances may be assigned to serve one ormultiple applications for mitigating potential denial of service (DoS)attacks as well as to improve domain administration and signallingefficiency. The AF may select an NEF to send requests to the CN andsubscribes to network exposure events. The NEF re-selection may berequired to reduce the packet delay for control messages as well as loadbalancing, if needed.

One NEF instance can be configured to serve one or multipleApplications, one or multiple Network Slice instances, one or multipleDNs, one or multiple Geographical Zones, one or multiple DNAIs, one ormultiple UE groups. The NEF configuration information can be stored inthe CAPIF Core Function, NRF, or the AF.

During the movement, the V2X UE may be served by a different set of CNfunctions in different administrative domains. If V2X Application knowsthe trajectory of the vehicle, the V2X Application may select differentNEF instances, each for one administrative domain, to send AF-InfluenceTraffic Routing requests and subscribe to the CN event exposureservices. These procedures could be performed anytime by the AF to makesure that the control link between the AF and CN is ready to serve theUE whenever the UE enters an administrative domain.

The AF may cancel the AF-Influence Traffic Routing requests andunsubscribe to the CN exposure events at an NEF when the V2X UE is nolonger in an administrative domain.

During the lifetime of a PDU Session of a V2X Application, the NEF maybe (re)selected to support control messages exchanged between CNfunctions and the AF. FIG. 18 provides a high-level procedure for NEF(re)selection. The AF is currently served by a Source NEF (S-NEF). TheAF may want to connect to another Target NEF (T-NEF).

In accordance with embodiments of the present invention this procedureis illustrated in FIG. 18.

In step 1801, if the AF has not yet discovered a T-NEF, the AF discoversa set of T-NEF(s) by using the Service API Discover of CAPIF Corefunction as described in 3GPP TS 23.222, clause 8.7 [10]. The AF maysend the following query information for NEF discovery: DNN, S-NSSAI,External Group ID, and application information (Geographical Zone IDs,AF-Service-Identifier, DNAI).

In step 1802 the AF may subscribe to Event Exposure Services provided bythe T-NEF. The AF may use Nnef_EventExposure_Subscribe provided by theT-NEF to send event subscriptions to the CN.

In step 1803 the AF may send request to influence traffic routing to theT-NEF by using Npcf_PolicyAuthorization_Create service described inclause 5.2.5.3.2, as part of AF-Influence Traffic Routing procedure inclause 4.3.6.2 of TS 23.502. The T-NEF may perform PCF discoveryprocedure to identify the serving PCF.

In step 1804 the AF may unsubscribe to event exposure services of theS-NEF by using Nnef_EventExposure_Delete service, described in clause5.2.6.2.3 of TS 23.502. The S-NEF may cancel network exposure servicesprovided by the UDM, AMF, and PCF.

In step 1805 the AF may cancel the AF-influence traffic routing requestspreviously sent to the S-NEF by using Npcf_PolicyAuthorization_Deleteservice as described in clause 5.2.5.3.4 of TS 23.502.

The procedure in FIG. 18 uses some existing services of NEF. The onlyrequired change is to specify the information the NEF provides to theCAPIF Core Function for NEF (re)selection in TS 23.501 and TS 23.502,including: DNN, S-NSSAI, External Group ID, and application information(Geographical Zone IDs, AF-Service-Identifier, DNAI).

Additional work on NEF discovery may be specified in CAPIF framework.

Although the present invention has been described with reference tospecific features and embodiments thereof, it is evident that variousmodifications and combinations can be made thereto without departingfrom the invention. The specification and drawings are, accordingly, tobe regarded simply as an illustration of the invention as defined by theappended claims, and are contemplated to cover any and allmodifications, variations, combinations or equivalents that fall withinthe scope of the present invention.

We claim:
 1. A method comprising: sending, by an application function (AF) to a network function repository function (NRF), a request to discover network exposure function(s) (NEF(s)); sending, by the NRF to the AF, a response wherein the response includes AF identifier(s) of AF(s) associated with the discovered NEF(s) and application information associated with the discovered NEF(s) which includes application ID(s) that the AF(s) support; and selecting, by the AF, a NEF from the discovered NEF(s) based on received information.
 2. The method according to claim 1, further comprising: enforcing, by the AF, the selected NEF to serve a user equipment (UE), wherein the selected NEF is different from a source NEF serving the UE before the selection of the selected NEF.
 3. The method according to claim 1, wherein the method further comprises subscribing, by the AF, to event exposure services of the selected NEF.
 4. The method according to claim 1, wherein before the selection, the method further comprises: subscribing, by the AF, to event exposure services of the source NEF; sending, by the AF, an influence traffic routing request to the source NEF; unsubscribing, by the AF, to event exposure services of the source NEF; and canceling, by the AF, the influence traffic routing request with the source NEF.
 5. The method of claim 2 wherein the AF selects the NEF from the discovered NEFs to serve the UE upon receiving a trigger, the trigger resulting from one or more of UE mobility, load balancing, relocation of a NEF, denial of service attack, a reselection request.
 6. The method of claim 1 wherein before sending the response, the method further comprises: obtaining, by the NRF, a registration of the discovered NEF(s).
 7. The method of claim 1 wherein the received information further comprises UE information represented by one of an internal group ID, an IMSI group ID, an external group ID, an UE ID.
 8. The method of claim 7 wherein the UE ID is one of SUPI and generic public subscription identifier (GPSI).
 9. The method of claim 1 wherein the request includes UE information for the NRF to discover the NEF(s).
 10. The method according to claim 1, wherein the received information further includes network slice information associated with discovered NEF(s).
 11. The method of claim 1, wherein the request includes network slice information associated with discovered NEF(s).
 12. The method of claim 1 wherein the request includes the application information.
 13. The method according to claim 10, wherein the network slice information is represented by one of a single network slice selection assistance information (S-NSSAI) and a network slice instance identifier (NSI-ID).
 14. A communication system comprising: at least one processor and a memory storing instructions for execution by the at least one processor to implement an application function (AF) and a network function repository function (NRF), the AF and the NRF being communicatively coupled through an interface, wherein the AF is configured to send a request to discover network exposure function(s) (NEF(s)); the NRF is configured to send a response upon receiving the request from the AF, wherein the response includes AF identifier(s) of AF(s) associated with the discovered NEF(s) and application information associated with the discovered NEF(s) which includes application ID(s) that the AF(s) support; and the AF is further configured to select a NEF from the discovered NEF(s) based on received information.
 15. The communication system according to claim 14, wherein the AF is further configured to enforce the selected NEF to serve a user equipment (UE), wherein the selected NEF is different from a source NEF serving the UE before the selection of the selected NEF.
 16. The communication system according to claim 14, wherein the received information further includes network slice information associated with discovered NEF(s).
 17. The communication system according to claim 14, wherein the AF is further configured to subscribe to event exposure services of the selected NEF.
 18. The communication system according to claim 14, wherein the AF is further configured to: before selecting the NEF, subscribe to event exposure services of the source NEF; and send an influence traffic routing request to the source NEF.
 19. The communication system of claim 14, wherein the NRF is further configured to: before sending the response, obtain a registration of the discovered NEF(s).
 20. The communication system of claim 14 wherein the received information further comprises UE information represented by one of an internal group ID, an IMSI group ID, an external group ID, an UE ID.
 21. The communication system of claim 20 wherein the UE ID is one of SUPI and generic public subscription identifier (GPSI).
 22. The communication system of claim 14 wherein the request includes UE information for the NRF to discover the NEF(s).
 23. The communication system of claim 15 wherein the AF is further configured to: receive a trigger, the trigger resulting from one or more of UE mobility, load balancing, relocation of a NEF, denial of service attack, a reselection request; and upon receiving the trigger, select the NEF from the discovered NEF(s) to serve the UE.
 24. The communication system according to claim 16, wherein the network slice information is represented by one of a single network slice selection assistance information (S-NSSAI) and a network slice instance identifier (NSI-ID).
 25. The communication system of claim 14, wherein the request includes network slice information associated with discovered NEF(s).
 26. The communication system of claim 14 wherein the request includes the application information. 